Dave,
Yes, That is your engine block heater cord/plug hanging down. I have used ours in our last two coaches usually when we get ready to leave after Christmas for Florida to escape the Ohio winter.
Plug it in about an hour before you want to start the engine in temps below freezing and the engine will start like it is summer.
Of couirse you either have to be plugged into 110v or have the generator running.
I have used both ways, since we keep our RV in the RV storage area here at the home base due to regulations of only 24 hours of time RV permitted at the home for loading/unloading.
Ron