Brakes will “squeal” when your brake pads become worn or glazed over. This is a common and intended feature to let you know it’s time for a brake pad replacement. Depending on whether your brakes are drum brakes or disc brakes, your brakes can accumulate brake dust which can also make the brakes squeak when you apply the brakes. This can usually be fixed by cleaning the brake dust out of the system, applying brake spray which can help quiet the squeak, or if replacing the brake pads and rotors.