Daniel says in the episode that he doesn't know what "chaka" means but uses the word for the Unas name. After watching it again (I've honestly lost count how many times since it's one of my favorites) I think, and could be I'm just needing to crash but the word "chaka" actually means 'destiny' or 'fate'. I'm just going on the context that Chaka kept saying it over the course of the episode (the first time with him chanting it while his face is raised to the sky, and the last as he's parting from Daniel), and the fact he was on a rite of passage. He was trying to find his place, his destiny, and he ended up seeing Daniel as being part of a bigger destiny than he thought possible.
I hope that makes sense, my eyes are trying to shut on me here.