What is the 3rd of Newton's laws?

Every action has an equal and opposite reaction

The third law states that, a mass1 experiencing a contact force from a mass2, will generate a force of the same magnitude but with opposite direction of the original. In other words, if mass1 exerts a contact force on mass2, then mass2 will exert the same force on mass1.

If body A applies a force on body B, then body B will apply an equal and opposite force on body A

Newton’s third law is about action and reaction forces. For every Action force there is a equal and opposite reaction force. These forces act on different bodies and causes acceleration in the bodies depending on their mass.

For every action is an equal and opposite reaction

Whenever two objects interact, the forces they exert on each other are equal and opposite. So for every action there is an equal and opposite reaction!

Every action has an equal and opposite reaction. So to speak, when you're standing on the ground, your weight pulls you downwards. At the same time, a force called the normal reaction force is pushing your weight upwards. The normal reaction force makes it so that you don't go through the ground. Weight is balanced with the normal reaction force. Hope that helps!