battery cables

Both reds on the + (Positive) post.  The black and white (taped together) go to - (Ground).

Since it is taped to the black/battery ground, that would be a good guess. Can you trace it? Does it go to the power tongue jack?

i don't have a power tonged jack

White is the grounded neutral as it is in your household wiring. So in this case it's the -12v connection. RV wiring typically follows the electric Code (white neutral, colored wires hot) not the automotive convention (black negative, red positive). Your trailer is a moving house after all, not a car.

Can be confusing for sure, and if you're not the original owner who knows what a previous owner might have miswired. So if youre uncertain and don't have one, get a multimeter and confirm what you have before connecting. Keep it in your on the road toolbox, it won't be the only time you'll use it.

In this case there are lots of clues all pointing the same direction so you can be pretty sure those two smaller gauge wires go to the Zamp connector on the rear side of the trailer. If you're not using that then you can also just leave those two wires disconnected if you want.

Zamp is the brand of the solar system that RPods used to use. The connector on back for solar had a label with that name. The red wire has the same brand name. I think a different brand is now being used. Zamp is likely good, but very expensive. I have a Renogy folding suitcase 100W solar system. That was expensive enough.