It's a casual greeting often used among friends.
Here's a breakdown:
* Ke onda: This is a shortened form of "Qué onda," meaning "What's up?" or "What's going on?"
* Ases: This is a shortened form of "asesino," meaning "killer," but in this context, it's used playfully, like "dude" or "man."
* O: This is simply the Spanish word for "or," which can be used as a filler word or to emphasize the greeting.
So, the entire phrase is meant to be friendly and casual, like a way of acknowledging someone and asking how they are.