They're used (often by males) when talking to friends. They are polite and yes I have had people who didn't really know me well call me "bro", too, but I don't think anything bad of it. "Man" "bro" "buddy" are just friendly ways of calling someone your friend, basically. I wouldn't address an older person with those names though, since it would seem like I think we are on the same level. English and Japanese are different when it comes to this. We don't have many polite ways of addressing people, only "Mr" or "Mrs." Normally, I call someone "bro" if that person is a good friend of mine or if we have talked a lot. "bro" is a shortened form of "brother", so calling someone your "bro" is like calling someone your close friend. I wouldn't say it to someone I just met. You can use it whenever you feel like it, if you don't feel comfortable saying it, you don't have to.

Normally, if you're a man, you'd say any of those words to your friends, but probably not your family, boss, etc. There aren't a lot of respect words in English, but for example "Sir" is pretty useful in any situation where you want to show respect. A waiter would say "Hello, sir", as might a receptionist answering the phone if they were being polite. The female equivalent is Ma'am or Madam (old fashioned) or Miss (for a young woman).

Thank you so much I realized the meanings I'll try to use the words to friend but I'm still shy to use the words and I can't speak english fuluently yet anyway thank you so much bro haha