Guessing this is a fuel tank level sender (coax?). It was hooked up to an electronics international fuel gauge however the wiring was an absolute disaster. No idea if it worked or not.
Interested to know what specific sender this might be and will work with Dynon skyview or not.
Almost certainly a connection point for a capacitance fuel level probe... unless you're still using UHF TV antennas and have need to watch movies in flight.
Place a multimeter on the two terminals and make sure its working then sort out the wiring. Capacitance fuel probes are very simple and very reliable so hopefully you won't need to go fishing inside the tank to get it operational again. Having said that, it appears to be in a very strange location at the top of the tank????