وَكُلَّ شَىْءٍ أَحْصَيْنَـٰهُ كِتَـٰبًا
Sentence structure
كُلَّ شَىْءٍ is fronted for emphasis and governed by an understood verb explained by أَحْصَيْنَـٰهُ. This is the construction of preoccupation اشتغال. كِتَـٰبًا describes the manner of enumeration: recorded in writing.
وَكُلَّ — and every
Grammar: وَ is a conjunction. كُلَّ is an accusative object of an understood verb explained by أَحْصَيْنَـٰهُ, and it is مضاف.
شَىْءٍ — thing
Grammar: An indefinite genitive masculine noun and the مضاف إليه of كُلَّ.
أَحْصَيْنَـٰهُ — We have enumerated it
Grammar: أَحْصَيْنَا is a form IV first-person plural perfect verb; نَا is its subject and هُ is its object pronoun referring back to every thing.
كِتَـٰبًۭا — in a written record
Grammar: An indefinite accusative masculine verbal noun functioning circumstantially حال, with the sense “recorded in writing.”