“وَ” (wa)means “and.” It is a preposition: it links this word to the next word or phrase.Corpus grammarP — prefixed preposition.
“الْ” (al)the Arabic equivalent of “the.” It makes the following noun specific.Corpus grammarDET — prefixed definite article.
“كِتَٰبِ” (kitābi)means “By the Book” in this verse. It is a noun. a naming word. Here it is masculine, genitive.Corpus grammarN — genitive noun.