it's a duplicate but I'm just going to clarify a few things here, the small lights are called collision lights or navigation lights, those are designed so the aircraft can be seen in dark or low view conditions.
the big white light is called a landing light because it illuminates under the aircraft for it to see the ground in dark or low view situations, it can eventually be used as a searchlight but a searchlight would probably be more of a mobile light that you can move around.

thanks, gonna edit that