What does protruding disk with mass effect mean?  

It is basically a herniated disc that hasn't exploded but it is pushing on the mass of your spinal cord to some degree. Sometimes, over time, these discs can kind of settle back into place.

I had this a l3-l4 and l4-l5 and the higher one mostly went back in on its own after a year. I had traction and everything but I really think it calmed down after my injury and kinda healed itself.