The brake help option is like a dumbed down version of ABS - it tries pumping the brake for you when the front wheels are about to lock up. It can unnecessarily increase your braking distance and actually remove control from the user, though I guess it's ok for newbies who really struggle with the brake pedal (or of course if you're using a gamepad it can help quite a bit). Once you have a proper wheel though you should disable it, as it just promotes bad habits.