Auton is short for Autonomous. The autonomous portion of an FTC match is thirty seconds. Your robot will have to move on it's own to complete the objective. Essentially what it is, is the robot moving by itself with code.
TeleOp has one to two drivers, controlling the robot with gamepads. This goes on for the majority of the match. But before that portion is the autonomous period, fully done by the robot.
In the next lesson, we will be making a basic autonomous program that programs the robot to drive in a square.