That would be the valve for filling the livewell. One way fills it. The other may drain it, or something like. that. I never used one myself but that’s what they do. I suppose you can look up on how they work exactly.
Remote live well drain valve, It is now in the closed position, when the handle in over the empty square it is open. To test it while the boat is on the trailer put water in the live well. It should hold water, move it and you should see water run out onto the ground. When you don't plan on using the live well leave it in the closed position when boating.
