Sanger mercruiser engine help?

Last summer we noticed that our vdrive engine seemed to leak water lots. A couple of times if we accidentally didn't have our bilge on, the engine area would fill up and would become a problem. We figured it came from this spot here back by the bilge pump. I'm just wondering whether this is normal, what this part actually does as me and my dad are not experts, and also what we should do to fix it. Any help is greatly appreciated. Thanks.