What is Force ?

Force is commonly called as push or pull. If force has an effect on a movable objects the object will tend to accelerate. the result of the effect of force is therefore always a changing velocity. on stationary objects, if not just a single force but several forces are acting on an object , It  not just a single force but several forces are acting on an object at the same time, these may sometimes cancel each other out. For example if a book is sitting on a table the net force is zero, i.e, the gravitational force is equal and opposite to the force the table exerts on the book

Force is an energy that make the stationary object to move and moving object to be in rest.

Here boys is applying force on girl and making him to move