وُجُوهٌ يَوْمَئِذٍ مُّسْفِرَةٌ
Sentence structure
وُجُوهٌ is a nominative topic. In one grammatical reading, مُّسْفِرَةٌ is its predicate; another recognized analysis takes it as an adjective and continues the predicate into ayah 39. يَوْمَئِذٍ is a time adverb.
Ayah summary
On that Day, the faces of the believers will be radiant.
وُجُوهٌۭ — Faces
Grammar: A nominative broken-plural noun functioning as the topic.
يَوْمَئِذٍۢ — that Day
Grammar: يَوْمَئِذٍ is a time adverb functioning as the linked complement.
مُّسْفِرَةٌۭ — (will be) bright
Grammar: A form IV, feminine singular nominative active participle agreeing with the non-human broken plural وُجُوهٌ. It is the predicate in one grammatical reading; an adjective reading is also recognized.