HELP -- what does "mounting disc" mean at the end of first aid disk utility for macbook pro

At the end of my "verify disc" session, one of the last statements in the window says " mounting disc ", the one before that says " The volume Macintosh HD appears to be OK." Below on the window in the rt. hand bottom corner is the blue bar like computer is working and beside it says "mounting disc." It has been in this spot for quite some time now. When I click to quit disk utility, it gives me the message " Operations still in progress. Quitting in the middle of some operations can leave a disk non-operable. Are you sure you want to quit?" Of course I clicked "don't quit". HELP