If its a used trailer, a previous owner probably installed a dedicated 115V inlet port for things like a space heater. There is currently a thread going on about that here
. There's probably a pigtail or outlet somewhere that is not active until an outdoor extension cord (you should use a heavy-duty 12-guage) is connected from the power post 115 outlet.
As far as the cable, one is for external park cable (which switches alternately with the rooftop antenna via the push button on the booster) and the other will be for satellite. The satellite is separate so you don't inject power to a cable system.
2015 Rockwood Signature UltraLite 8282WS Platinum, GY Marathon LRD, TST 507RV TPMS
2005 GMC 2500HD CCSB D/A, Curt E16, Prodigy P2, Garmin RV760LMT w/BC-20 b/u cam