Depending on where your house is located, you might need a sump pump in your basement. The purpose of this is to keep groundwater from seeping in to your basement from below, or surface runoff from making its way in. Your sump pump will activate automatically when it senses a rising water level under the lowest part of your basement floor, and it will pump it out to a location away from your house.
You can test the operation of your sump pump by pouring water into the trench and checking if the pump activates.
To maintain your pump, keep it on a regular cleaning schedule, and the more often your pump runs, the higher the frequency of cleanings should be. It is important to check that the float that activates the pump when the water level rises isn’t stuck, since this will prevent the proper operation of the pump.