Step-by-step explanation:
A free body diagram shows all the forces acting on a body. It gives the magnitude and direction of the number of forces acting on an object when it is in equilibrium.
For example,
When a force applied to an object is F. The force of friction also acts on it in opposite direction. Its weight is also acting in vertically downward direction. One normal is also acting on it.
It shows that all type of forces acting on the object i.e. normal force, gravitational force, frictional force and the applied force.