“فَ” (fa)This word resumes the flow after a pause or change in thought.Corpus grammarREM — prefixed rem particle.
“كَفَرُ” (kafaru)means “But they disbelieved” in this verse. It is a verb. an action or state word. Here it is perfect verb, third person — masculine — plural.Corpus grammarV — third person masculine plural perfect verb.
“وا” (wā)an attached pronoun meaning “they” or “them.”Corpus grammarPRON — third person masculine plural subject pronoun.