From the picture in your post it appears that the power cord has been removed from the 4x4 box on the right side, There is one knockout removed and there are two EMT clamps visible on the right side of the box which would have been used to hold the shore cable in place. The shore cable would of been tied into the wires in the 4x4 box and then it would of had a blank cover on it. Like Executive said when using the generator you would unplug your shore power cable from the CG pedestal and plug it into the receptacle on the left side of the picture. My MIL had an older camper like that. In your OP you said that you did not know about electricity, you might want to talk with an electrician about this. It's an easy job for them to do this. JMO