It's a toggle switch. If it's pointing towards the window, it allows the electric heater in the fireplace to work. If it's pointing towards the center of the camper, it allows the electric water heater to work.
My dealer explained both are tied into the same fuse and so they put in the toggle switch so you don't overload things by trying to run both (the fireplace being an option that I suppose many don't have, but we happen to have one)
EDIT: Ran out to take a picture to show you how mine is labeled
2013 GMC 2500HD Crew Cab SLT 4x4, 6.0L
2016 Jayco Eagle HT 29.5 BHDS