Definitions differ, but for me ‘an edge’ is simply one session of masturbation without cumming. Simple as that. I don’t count each time you ‘bounce’ on brink of an orgasm an edge, I call that ‘riding the edge’ and it still only counts as one.
If you’re wanting to rack up numbers for a task like ‘you can cum after 100 edges’ then I’d add a rule like ‘an edge only counts if you haven’t edged for five or ten minutes’ so forcing them to stop, or calm back down a bit before going for it again, and that then limits it to a few an hour and makes them take it slowly.
If you want to narrow things down further then you can have a ‘soft edge’ which is where you don’t even get close to cumming, on purpose. Either because it’s just a ‘quickie’ or because they keep going over if they edge too hard.
Which brings us to a ‘hard edge’ which is the opposite, it’s where you take yourself right the brink of orgasm, as close as you can without going over.
I hope that helps, good question, thank you!