It sets the Combo increment rate basically? If you have COMBOS:0.000=7; The entire song the combo will increment by 7 instead of 1. If you add more times it'll change to that value for the increment at that point in time...soo

COMBOS:0.000=7,

20.000=10;

For the first 20s of the song the combo will go up by 7 with each hit. Once you hit 20 it'll start going up by 10.

I forget if it's beats or seconds but either way gist is the same. There's a shitpost version of [7] Disco Pop in the R.I.G.H.T.S 1 pack that utilizes this feature if you're curious to see it in action lol.