When coming to a stop and applying the brakes.

If the noise is being created by applying the brakes -have the brakes inspected further-could be due to worned out disc pads-etc

Grinding brakes is real common when you don't have them inspected periodically. That's a normal maintenance item. Very often the rotors can be machined as a normal part of any brake job as long as they remain above the minimum published legal limit, but once they start grinding you and assume they'll be too thin to save. New rotors are relatively inexpensive today so many mechanics just replace them to save time and cost rather than machine the old ones.

Have your brakes inspected right away. Expect to need new brake pads and two new rotors.