HHHHHHHEEEEEEELLLLLLPPPPPPP!!!!!!!!

Can someone please tell me the what, why, where, etc. of a hose that I have no idea about but is the source of leakage in my cooling system. The hose is approximately 1/4 - 3/8 inside diameter and about 5/8 - 3/4 inch outside diameter. It exits the engine from what appears to be behind the alternater, don't know exactly origin, possibly water pump area or some other part of the cooling system. Does a leak out of this hose mean too much pressure is building up in my cooling system and/or a bad water pump and thus the source of my constant overheating problem.

1993 190E 2.3