Some area of erosion & marrow edema of humeral head near the intersection of the supraspinatus tendon. Some red marrow replacement. What'sdoes itmean?

Shoulder impingement. You could be suffering from a condition called shoulder impingement where the rotator cuff (supraspinatous is one of the tendons that is part of rotator cuff) is "impinged" by bone above it and sometimes can result in irritation at the insertion on the humerus. This can result in bone edema and inflammation which can present itself as shoulder pain with certain motions.