'buddy' means friend but it is a less formal and more casual term and is not usually used in formal texts, but is usually spoken instead. some people say the word when they are talking to a friend e.g 'hello, buddy', 'how have you been buddy?' which is the same as saying 'hello friend', and 'how have you been friend?'. hope that helps and someone corrects me if im wrong :)

Bilkis is absolutely correct with her answer. The only thing I want to add is that it is a term used between men. Women do not usually have "buddies." There was a popular World War I song entitled "My Buddy." I think that's when the term originated. But I could be wrong.