* Newton's Third Law: For every action, there is an equal and opposite reaction. This means that when the man pushes on the wall with 50 N of force, the wall pushes back on him with an equal force of 50 N.

* Size: The wall exerts a force of 50 N on the man.

* Direction: The wall exerts this force directly opposite the direction the man is pushing. If the man is pushing to the right, the wall pushes back to the left.

Important Note: While the forces are equal in magnitude, they don't cancel each other out. This is because they act on different objects (the man and the wall). The man doesn't move because the wall is stationary and strong enough to resist his push.