This is a marine utility pump that runs off a 12 volt battery.
Is has no plug. Can it be converted to run off 115 household socket??

If you want to run it from the wall, you'll need to go buy a 12V DC power supply. The only problem is that you need to make sure to buy one that can handle at least as much current as the pump draws, and unfortunately that might be quite significant (10 amps or more), depending on the size of the pump. A power supply which can handle that much current can be quite expensive. Does the pump happen to have a label that indicates how many amps it draws?

In any event, the pump most likely has a red wire and a black one. Usually the red wire is the positive terminal and the black is the negative (a.k.a. ground). Whatever power supply you end up getting will correspondingly have a positive and a negative wire. You just need to hook positive to positive and negative to negative.

Depending on how much water you want to flow, it may be cheaper to buy a 120VAC pump. HD and Lowe's have them. Harbor Freight routinely sell 1/6 HP ones for <$50($40 last week). If you have a decent battery charger, it will power the 12VDC pump.

The power supply out of an old computer can also make a good 12V DC source for large loads like this pump. The +12V wires are usually yellow and the ground wires are black. (See here for a more in-depth description with pictures).

Assuming your pump uses the red/black wire combination I mentioned before, you'd cut one yellow wire from its connector on the power supply and hook it to the red wire on the pump. Then you'd cut one of the black wires and hook it to the black wire on the pump. A couple of wire-nuts or some electrical tape is all you should need to insulate the connections.