Every action has an equal and opposite reaction” is a statement of Newton’s third law of motion:

This law states that when one object exerts a force on another object, the second object exerts an equal and opposite force on the first. The “action” and “reaction” refer to forces that act on two different bodies.

For example, when you swim, you push the water backward, and the water pushes you forward. Similarly, when you walk, you push the ground backward, and the ground pushes you forward.
His third law states that for every action (force) in nature there is an equal and opposite reaction. If object A exerts a force on object B, object B also exerts an equal and opposite force on object A. In other words, forces result from interactions.
Examples of action and reaction involving aerodynamics:
The motion of lift from an airfoil, the air is deflected downward by the airfoil’s action, and in reaction, the wing is pushed upward.
The motion of a spinning ball, the air is deflected to one side, and the ball reacts by moving in the opposite direction.
The motion of a jet engine produces thrust and hot exhaust gases flow out the back of the engine, and a thrusting force is produced in the opposite direction.