You're gonna be a yoga practicing lifeguard? :-) just kidding
Honestly, it probably means that the hours are flexible, and you're in a job pool / employment agency sort of situation. So the hours aren't regular, you get the jobs as they come available, but there are other people in the "pool" that are also being assigned jobs / hours out of the same "pot" so to speak.
That. or it was a serious typo, and they meant flexible. But I would ask the company that you applied with and ask them what, exactly, they mean by it, and what sort of hours you could hope for with them.
at 8:11 AM on Dec. 29, 2009