Interessante Verkabelung für das Backbord-Einfahrtslicht.

It is for grounding. That is not the ideal way to do it, but it does serve the purpose of ensuring that anyone touching the metal of the pole or anything connected to it will be standing on something which is at the same potential so that they don’t get electrocuted. I see there is also a wire going off towards the water, which I hope goes somewhere that ensures a good connection to actual earth.