DPST means Double Pole, Single Throw.
Double Pole means that there are two separate switches. Typically if you look at the axis of motion the terinals on one side of the axis will be one switch and the terminal on the other side will be the other switch.
Single Throw means that the two switches are either ON or OFF.
The lamp should be suitable for 110 to 250 volts.
Assuming two terminals are near the middle of the switch and two are near one end I would expect the middle ones to be the inputs and the end ones to be the outputs. I would further expect the lamp to be connected to the outputs so if you wire in reverse (power in the outputs and out the inputs) the lamp would be on all the time.