Isolated ground recepticles are to be mounted in metal boxes so that the recepticle yoke (via the captive screw clip and the mounting screw) are grounded by a seperate grounding means than the "U" terminal. In your case the bare copper wire (romex multistrand?) is connected to a 10-32 green grounding screw added to the back of the metal box.
In installations using metal (thinwall) conduit the conduit acts as the seperate grounding means.
In installations using metal (thinwall) conduit the conduit acts as the seperate grounding means.