Low Brake Fluid problem

alright i just recently bought a 2000 LS V8 and a couple of days ago the low brake fluid warning comes out on the info thing where the speedometer and everything is. I check the brake fluid and it's full. The light turns on n off it hasn't turned on a lot so i haven't noticed any kinda of pattern or anything but does anyone know wut the problem might be. Thanx for your input

The place where i bought it said to reset it buy pumping the brake. Does anyone know how to do this?