For every action there is an equal and opposite reaction. What does this sentence imply?

Action and reaction event occur in pair and their magnitude is same but of opposite nature.

Explanation:

The statement is Newton's third law of motion. It means that in any interaction, for a pair of objects. Pair of force acts on them. The magnitude of the paired forces is equal and work in opposite direction to each other. Hence, suppose if object A applies X amount of force in one direction on object B then object B in reaction will also apply X amount of force but in opposite direction in relation to that of applied by object.

This statement enables to solve many phenomenon related to motion such that motion of human in which when we external force in backward direction from out foot and equal amount of force is exerted by force of friction in forward direction on our body and we are able to move.