كِتَـٰبٌۭ مَّرْقُومٌۭ
Sentence structure
كِتَـٰبٌ is the nominative predicate of an omitted topic, and مَّرْقُومٌ is its nominative adjective.
Ayah summary
Illiyyin is a written register containing the names and deeds of the people of Paradise.
كِتَـٰبٌۭ — A book
Grammar: An indefinite nominative noun functioning as the predicate of an omitted topic.
مَّرْقُومٌۭ — written
Grammar: An indefinite nominative passive-participle adjective describing كِتَـٰبٌ.