means A pivoting lever you tilt or push to control something — originally an aircraft's flight controls, later video games, drones, and other machines.

from Early aviation slang from the dawn of powered flight, when pilots called the control column the "joystick." Why "joy" is the unsettled part: the cheeky guess is that it points to the literal joy of flying (or a cruder anatomical pun on a vertical lever between the legs), but the true origin is undocumented — it bubbled up from cockpit slang and stuck. The pilot itself was sometimes called the "joystick," and the name later glided naturally to the controllers of arcade machines and home consoles.