What is what does oi mean?

Oi is an informal greeting that originated in Brazil and is now commonly used in other Portuguese-speaking countries. It is similar to "hey" or "hi" in English. In addition to being a greeting, it can also be used as an exclamation to get someone's attention or to express surprise. In some subcultures, particularly in the UK, it is also used as a slang term for a working-class punk or skinhead.