Looks like a standard 12V SAE power port. Given its location you should be able to follow the wires behind it pretty easily and I'd bet they're black/red and go to your battery, possibly through a fuse or breaker (ideally).
I've never seen one factory-installed so perhaps it was a dealer add-on or previous owner? I install them on every camper I buy. They're insanely useful. I've used them for:
1. Solar battery tenders to keep the battery charged in storage.
2. Tire and air-mattress inflaters
3. Spare 12V RV water pump, they're cheap on Amazon. Add a garden hose cut in half (one half on each side of the pump) and an "Aquatank" bladder (also cheap on Amazon) and say goodbye to worries about keeping fresh-water tanks full when boondocking or at campgrounds with no water.
4. Aux lighting - a 12V LED light rope/strand on your awning uses a lot less power than a typical 120V one fed off a generator or inverter. Also, although I had to throw it out now (wind storm tossed and broke it) I once had a light rope on the handle of a hoe that I tack-welded to an old brake rotor as a base. This made a perfect portable light pole to set up where I parked my truck.
5. If you have a boat with an electric trolling motor or similar and need a way to charge its battery, this is an easy win.
There are tons of uses for 12VDC around camp, and those connectors are very standard and easy to find in any hardware/auto/etc store.