DIAGNOSIS Sounds like the wheel brake is partially engaged or the self-propel gearbox for that wheel is binding. These mowers have a parking brake that acts on the rear wheels, and if it doesn't fully release, it drags.
FIX First, check the obvious. Make sure the red parking brake lever on the handle is fully disengaged (pushed forward). If it is, lift the mower so the noisy wheel is off the ground. Spin it by hand. If it's grinding and hard to turn, you likely need to remove the wheel to check for a stuck brake pad or debris wrapped around the axle.
IF THAT DIDN'T WORK If the wheel spins freely off the ground but grinds under load, the issue is inside the self-propel gearbox attached to that wheel. For that, you're probably looking at a gearbox replacement, which is a whole project.
HEADS UP Never engage the parking brake while the mower is still moving, even slightly. It's meant for a full stop on a flat surface. Slamming it on while rolling is a great way to warp the brake mechanism and cause this exact drag.