The phrase "to press the switch" means to push down or activate a small device, usually with your fingers, in order to turn something on or off. Full definition
The wheel mode shift button is another highlight of this design - pressing it switches between two different scroll wheel settings. (pocket-lint.com)
Drivers pressed a switch attached to a thumb when they saw the light. (sciencedaily.com)
The most common objective is to just get rid of all enemies on the map, but there are some different scenarios like pressing switches or collecting some keys every now and then. (waytoomany.games)