Some brake pads have a built in "squealer" to worn the driver that the brakes are in need of service soon. Have a trusted mechanic inspect the brakes soon. Waiting may cost you more money in repairs.
At least inspect when you hear squeal. Base further work on what you see.
hypothisies
hypothisies
the brakes use friction to stop the car
The brake pad "squealers" are telling you to have the brakes checked.
Bad logic
theory
Foot brakes are used to stop a car. In an emergency however both the foot and hand brakes can be used to stop a car.
Friction is what makes the brakes stop the car.
Your brake system needs repair immediately. The brakes are squealing because the pads are worn out, and you are hearing the warning device or the metal to metal contact of the pad and rotor. Stop driving the car and have the brakes repaired. The ABS light may or may not go out. If it does not, there is problem with the ABS. Your standard brakes will still work.
Brakes use friction to stop a car.
The car breaks (brakes) stop the car.