Here's why:

* Balanced forces mean that the forces acting on the object are equal in magnitude and opposite in direction. This results in a net force of zero.

* Newton's First Law of Motion states that an object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

In simpler terms: Think of a tug-of-war with two teams pulling equally hard on the rope. The rope won't move because the forces are balanced. Similarly, a book on a table experiences balanced forces: gravity pulling it down and the table pushing it up. The book stays still.