it is

My is an attributive pronoun related to mine, a predicative pronoun.

My book. The book is mine. Predicates are verb things. I don't know what attributive means. I might have known once (verb tenses, very interesting things) since I recognize the word, but again don't recall.

My furnature might be part of a noun phrase, but it should also fit a particular speach usage. I'm still guessing adjective.

I'm booking it out of here.
Congress is vetting nominees.

And then there's gerrunds and gerundives. I don't think I was ever clear on them. I don't think they were mentioned much. I don't know what they are. Something about adding 'ing' to nouns and/or verbs. Or something else? I can absolutely look that up.