It "could" be a ground. White wires are "usually" ground on RVs.
Not much info provided. Wiring can be different RV to RV. Even same models.
Any signs of a connection point in the area as the wire end appears frayed? Does the wire loop down and back up to the right side of the box? (looks like it in the pic) Have you followed the wire to where it may lead?
2016 Attitude 28SAG
2012 Ram 3500 CTD
2008 Kawasaki Vulcan Nomad
2007 Kawasaki KFX 700