What is whats up brother?

"What's Up, Brother?" is a phrase that is generally used as a casual greeting among friends or acquaintances. It is often used to inquire about someone’s well-being or to start a conversation in a friendly and informal manner. The word "brother" is typically used in a non-literal sense to denote camaraderie or solidarity, and it is not necessarily limited to actual siblings. If you are referring to a specific cultural reference, song, or media that includes this phrase, providing more context would help in offering detailed information.