Whats wrong? Your brakes are not working correctly; they are NOT
"fine."  That's what the light on the dash means.

If you are typical and fortunate, you've never in your life experienced
anti-lock brakes doing their job.  In order to experience working
anti-lock brakes, you must suddently stab the brake pedal with your
full weight...the car will shudder and vibrate in a way you've never
experienced as the brakes rapidly apply and release.  That is what
"anti-lock" does.  The purpose is to keep the wheels (all 4) from
skidding on the pavement (ice, water, sand, whatever) so you can still
steer and slow.

Go to a competent mechanic NOW and get your brakes fixed.