If you ask a rhetorical question it means you don’t necessarily expect an answer, but you do want an occasion to talk about something.
Rhetoric is the art of written or spoken communication. If you went to school a hundred years ago, your English class would have been called Rhetoric. But nowadays if we say something is rhetorical, we usually mean that it’s only good for talking. If you speak beautifully about carpentry but can’t ever actually build a cabinet, we might say you have lots of rhetorical flare, but very little real skill.