You probably have a bearing that needs to be replaced.
Why Would A Grinding Noise Happen While Turning Left In Reverse?
If it is a hard left it would be that you are up against the steering stops and this would be normal.
Is it a front wheel drive? Could be a CVC joint in the front axle or the rack and pinion going bad. Look under the car, if front wheel drive, and see if there is a rubber boot busted and grease slung out on the axle.