" The pressure" is described as the collision of the molecules of a fluid inside the surface of their container
Explanation:
When the molecules collide against the wall of the container, the molecule will be imparting momentum to the wall which as a result produce a force to the wall will be perpendicular. The sum of all the forces acting between all the molecules that are striking the wall will be divided by the area of the wall which will be due to the pressure. In order to know the pressure the force will be divided against the force by the area in which the force is being acting.
