Accusative Particle (إنّ) · حرف مشبه بالفعلإِنَّ means 'indeed' and carries the doubling shaddah ـّ; it pushes its own topic into the accusative — the ending usually shown by a fathah ـَ, a small slanted stroke above the final letter — while the comment about that topic stays in the nominative, the ending usually shown by a ḍammah ـُ, a small curl above the final letter. Here its topic is the attached هُمْ 'they', which it takes as its accusative subject — a pronoun keeps one fixed shape, so no fathah appears, but the role it fills is the accusative one: 'indeed they…'. L15 · R3

Attached Pronoun · ضمير متصلAn attached pronoun is a mini-word glued onto another word. The ending هُمْ on إِنَّهُمْ is such a suffix, standing for 'they' — the topic that إِنَّ takes as its subject. L3 · R6

Detached Pronoun · ضمير منفصلA detached pronoun is a standalone word for 'they', 'you', 'I', and the like. هُمُ is the standalone word 'they', placed between 'indeed they' and 'the corrupters' to fasten the two together. L3 · R2

Subject (Mubtada') · مبتدأThe subject is a noun a sentence talks about — its topic — and it stands in the nominative, the 'topic form' usually shown by a ḍammah ـُ, a small curl written above the final letter. هُمُ 'they' stands as this topic — a pronoun keeps one fixed shape, so no ḍammah appears, but the role it fills is the nominative one — and what follows, 'the corrupters', is what is said about them: it is they who are the corrupters. L6 · R2

Definite Article · أل التعريفThe definite article is the prefix ٱلْ at the front of a noun (a naming word); it means 'the' — one specific, known one. The letter after it is a 'moon' letter — a letter not made in the same part of the mouth as ل — so the ل of the prefix keeps its own sound, both written and heard, resting with the sukūn ـْ (a small circle written above the letter): ٱلْمُفْسِدُونَ. L2 · R9

Noun · اسمA noun is a word that names a person, place, thing, or idea. مُفْسِدُونَ is such a naming word: '(are) the ones who spread corruption', from the root فسد: to spread corruption, cause ruin, corrupters. L1 · R6

Masculine Noun · اسم مذكرArabic treats every noun — every naming word — as grammatically 'he' or 'she'. Even as a plural, ٱلْمُفْسِدُونَ carries no feminine marker — no ة at its end, no final ى, no اء — so it takes the default and is a masculine noun; its ending is the 'sound' plural ending Arabic reserves for masculine nouns. L2 · R3

Plural Noun · جمعA plural noun refers to three or more of something. The sound masculine plural carries its role in its ending — ـُونَ for the nominative (the 'subject form', with the ḍammah ـُ sound), ـِينَ for the accusative and genitive (the 'object' and 'of' forms); ٱلْمُفْسِدُونَ closes with exactly such an ending: not one, but a whole group. L2 · R6

Nominative · مرفوعThe nominative is the ending a naming word takes when it completes what is said about the topic; for this kind of plural that ending is ـُونَ. ٱلْمُفْسِدُونَ carries that ـُونَ ending in its own right, as the comment about 'they': they are the corrupters. L2 · R6

Predicate (Khabar) · خبرThe predicate is the part that tells you something about the topic, in the nominative ending. The topic was هُمُ 'they'; ٱلْمُفْسِدُونَ is what is said about them — the corrupters — standing nominative in its own right. L6 · R3

Active Participle · اسم فاعلAn active participle is a naming word built from a verb's root to name the one who does the action. Built from the root فسد (to spread corruption), ٱلْمُفْسِدُونَ names the doers — those who work corruption, 'the corrupters'. L11 · R3

Supplementary Particle · حرف زائدA supplementary particle is an extra word added for weight, whose removal would not change the core meaning. The prefix وَ here rides along with 'but', adding to the flow without altering the sense. L14 · R4

Retraction Particle (بَلْ / لَٰكِن) · حرف إضراب واستدراكA retraction particle like لَٰكِن 'but' adjusts or qualifies what was just said, steering the sentence in a new direction. Here لَٰكِن turns from stating that they are the corrupters to noting what they fail to grasp: 'but they perceive it not'. L20 · R18

Particle · حرفA particle is a small helper word of one to three letters that works like glue — it connects or adjusts other words rather than naming something or describing an action, and it can never be the one a sentence is about. لَّا · 'not/no' is such a helper. L1 · R9

Negation Particle · حرف نفيA negation particle is a word meaning 'not'. لَّا negates the present-tense verb after it: 'they do not perceive' the corruption they work. L4 · R5

Verb · فعلA verb is a word for an action or happening that is always tied to a time — past, present/future, or a command. يَشْعُرُ is an action unfolding now: 'they realize (it)', from the root شعر: to perceive, know; poetry, poet; sacred symbols/rites. L1 · R7

Present Tense Verb · فعل مضارعA present-tense verb describes an action happening now or still to come, and it is recognized by its opening letter — one of the four present-tense prefixes أ ن ي ت. يَشْعُرُ opens with exactly such a letter: 'they realize (it)', from the root شعر: to perceive, know; poetry, poet; sacred symbols/rites. L8 · R3

The Five Verbs · الأفعال الخمسةThe Five Verbs are the five present-tense shapes whose ending closes with the letter ن — يَفْعَلَانِ, تَفْعَلَانِ, يَفْعَلُونَ, تَفْعَلُونَ, تَفْعَلِينَ. يَشْعُرُونَ is one of them: its ending ونَ keeps that closing ن, and for these five shapes the kept ن is itself the grammar-sign that the verb stands in its plain, ordinary mood. L10 · R10

Attached Pronoun · ضمير متصلAn attached pronoun is a mini-word for 'I / you / he' that cannot stand alone — it is glued onto the end of another word, and each form carries within it exactly who is meant. ونَ · 'them/their' is fastened to the tail of the verb here — يَشْعُرُونَ — naming the one who did the action. L3 · R6

Doer (Fa'il) · فاعلThe doer is the one performing the action, so it stands in the nominative — the 'subject form', usually shown by a ḍammah ـُ, a small curl written above the final letter. The ونَ ending on يَشْعُرُونَ is that doer, 'they' — the ones who do not perceive; on this attached pronoun the shape is fixed, so no ḍammah appears, but the role it fills is the nominative one. L9 · R4