I would say that is the throw out bearing that is worn out. It is only spinning while the clutch pedal is pressed down so only makes noise then.
There may be a port on the side of the flywheel bell housing that will allow you to look in there a little. You may see a grease fitting and get excited that you can grease the bearing. That is not possible. That fitting puts grease between the shaft and the carrier of the throw out bearing not into the bearing. You can add a couple of pumps to the fitting and it could possibly help but I don’t think it will.
You will need to split the tractor and replace that bearing. While doing that I suggest you replace the clutch, pressure plate and guide bushing with new parts. Most of the labor is in splitting the tractor not replacing the parts. There are many threads on here to give you an idea of what is needed.
