Here's what that means:

* Action and Reaction: When one object exerts a force on another object (the action), the second object exerts an equal and opposite force back on the first object (the reaction).

* Equal in Magnitude: The forces are equal in strength.

* Opposite in Direction: The forces act in opposite directions.

Examples:

* Jumping: When you jump, you push down on the ground (action). The ground pushes back on you with an equal and opposite force, propelling you upwards (reaction).

* Rocket Propulsion: A rocket engine burns fuel and expels hot gas out of its nozzle (action). The hot gas pushes back on the rocket with an equal and opposite force, driving it forward (reaction).

* Swimming: When you swim, you push the water backwards with your arms and legs (action). The water pushes back on you with an equal and opposite force, propelling you forward (reaction).

Important points:

* Pairs of Forces: The action and reaction forces always act on *different* objects.

* Simultaneous: The forces occur simultaneously. One doesn't cause the other; they happen at the same time.

* Not Cancellation: The forces don't cancel each other out. They act on different objects, so they don't influence each other's motion directly.

Newton's Third Law is a fundamental principle of physics and helps explain how forces interact in the universe.