What is Newton's third law?
For every action, there is an equal and opposite reaction.
Newton's 3rd Law states : For every action, there is an equal and opposite reaction.
According to this law, forces always act in equal by opposite pairs.
Action and reaction force pairs don't cancel each other out because they act on different objects.
The downward force is the action force. The reaction force is the the force that is exerted.
Looking at the picture below, we see that when the force of the finger is against the wall, the force exerted by the wall is pressing back towards the finger.