Karen627 wrote on 12/31/69 at 16:00:05:Yep, that's for passing. Flashes the highbeam.
The salesman at the dealership where I bought my bike suggested I use that button if I'm at a red light in an intersection and the light turns green, to warn oncoming drivers that I'm there and coming through. Trouble is, at least around where I live, if you flash the highbeam at someone, they take it to mean you're letting them go. Quick and easy way to get yourself killed -- so I wouldn't recommend using it in intersections.
To get the same effect without giving the opinion that you're letting "them" go, get a headlight modulator for your bike....it will flash continuously then.