why did abs light come on

It means there is a problem with the ABS system. There are codes that can be read with an ABS reader. The problem is probably a wheel speed sensor.

If it stayed on you may have a broble. If you braked har it will come on momentarily to show that you invoked the ABS system.

ABS came up on my 2002 buick , cleared the code and hasn't been seen since , no problems braking

thankyou