That is a Blakes seacock. The way it turns depends on the position of the cone when the handle was attached. Assume that is a toilet outlet, so pump some water through and if it drains then it is open. BTW perhaps you should consider removing all thos wires which presumably go back to an anode or the engine. Completely unnecessary as the seacock is made of either bronze or DZR and does not corode. It should not be connected to anything else.
When the handle is at 180deg to the hose, the seacock is open.
If you scrub hard enough with brasso, you may just be able to see the arrow within the diamond at the head of the handle