Automatic  ("Auto")

An "automatic" car decides for itself when to change gear, and does it for you.  There’s no clutch pedal, so only two now: brake & gas.  (You use only the right foot, on one pedal at a time).

The car connects and disconnects its engine by itself, according to the work demanded of it, so won't stall like "a manual" if you suddenly give it too much work (i.e. try to move off too quickly).

Many autos have "creep", which means the car will very slowly move unless you keep your foot on the brake.

Autos are less tiring in stop/start traffic, smoother, and use less fuel (if new).  But they cost more (to buy and maintain), are less common, and use more fuel (if old).  And driving an auto means your licence is limited ... until you pass a manual test.