Does having the right to an opinion mean the right to give unsolicited advice?

Depends on how you look at it. On one hand, Americans have the right to freedom of speech, right? That means that you have a right to your opinion and you also have the right to express it, so you could say that you have a "right" to give unsolicited advice. On the other hand, do you have a "right" to poke your nose into someone else's business? Not really, unless you're in law enforcement and you're investigating someone for illegal activity...