'yo' is an informal interjection used as a greeting or to express enthusiasm, and can also be used as a call for attention or to refer to oneself or others in a casual manner.. She takes us back to the vault.
Yo / ˈ joʊ/ interjection britannica dictionary definition of yo us, informal — used especially to attract someone's attention, as a greeting, or in response to a greeting. Yo is a popular slang term that is used to address someone or get their attention.