Brakes should normally not grind or make any sounds while driving.
However sometimes rocks, dirt or other debris may get between the brake pads and rotors etc and cause the brakes to grind.
Also brake pads have a wear indicator on them that scrape against the brake rotors when the brake pads wear down and need replaced.
So when the brake pads wear indicator is scraping or grinding it's in indicator that the brake pads are worn down and need replaced.
So if your brakes are grinding when driving you should inspect the brake pads to see if they need replaced.
If you hear a constant screeching or grinding sound, even while not braking, it could mean you have something lodged in your brake caliper.
It could be anything like a small stone, a piece of gravel, or any small object.
Leaving a foreign item in the brake system can cause severe damage to the brake disc.
Sometimes grinding noises when driving can also be an indicator of worn wheel bearings so if the brakes are not the cause of the grinding then it could be the wheel bearings or wheel hub assembly needing replaced.