That’s pretty much it. They are playing best of three or five games yet refer to individual games as “sets”. I assume its just a carryover from tennis. I know, there can be one item in a set but usually it refers to a group of things.
As far as I can tell, “set” and “game” are synonymous in volleyball, and “set” has become official usage in 2008, at least in the NCAA, according to Wikipedia