Well, what you want to know when you're deciding on a switch is how much current you're breaking. Do you know if the pumps are chassis grounded or via separate ground wire? In case you want to break both the positive and the negative, then you'd need a DPDT switch as oppose to a SPDT one. That's Dual Pole, Double Throw vs Single Pole, Double Throw.
You could use Single Throw too, I guess, but then one of the pumps would always run unless you have one more switch as a master (such as the ignition switch).
Double throw has an OFF position in the middle and two ON positions. ON-OFF-ON. Single Throw are ON-ON.
They all have three connectors per pole, the middle one connects to one of the outer ones. DP switches have two rows of three connectors.
Most switches connect to the connector OPPOSITE of the direction of the throw.
