The action and reaction when a person is walking on the floor are
Action- force to push the ground backward, Reaction- Force by ground on our feet forward
While moving on the ground, we exert a force by our feet to push the ground backward, the ground exerts a force of the same magnitude on our feet forward which make us move forward. Hence, the action is the force to push the ground backward and the reaction is the force by the ground on our feet forward.