I recently moved into a home and this was lying on a shelf untouched or plugged into anything. Thanks]1
This is a pump control box made by BURCAM and this link is the datasheet.
From your comment about a pump sitting next to it, this looks like the previous owner had a project they either never completed or had to go a different route in completing that required a pump. As others have stated, this unit appears to have never been installed.
It's purpose is this:
A single phase AC induction motor requires a "capacitor start" routine to make it start spinning in the correct direction, because single phase power has no relative rotation, so without the capacitor starting, the motor would either just vibrate back and forth, or spin in either direction randomly each time you start it. But on a "standard" capacitor start motor, you can see that the capacitor is attached to the motor, that big "lump" on the side of it (some have two, because they need one for running too). That starting capacitor is also not needed once the motor begins spinning, so it is switched out of the circuit with what's called a "centrifugal switch" mounted to one end of the motor, under the bell housing.
But on a submersible pump motor, you need the motor to fit down inside of the well casing pipe, so there is no room for that lump on the side. Plus, the centrifugal switch is a part that wears out and has to be replaced. Replacing parts on a pump motor that is deep under ground becomes expensive. So the solution to both problems is that the starting capacitor is put in that box (the round black cans that you see in there), and the centrifugal switch is replaced by an electronic device called a "potential relay" (the square cube with all the wires coming out of it).