Yes, that statement is true and is a fundamental principle of physics known as Newton's First Law of Motion, also known as the Law of Inertia. Here's a breakdown:

* Inertia: Inertia is the tendency of an object to resist changes in its motion. An object at rest wants to stay at rest, and an object in motion wants to stay in motion at the same speed and direction.

* Net Force: Net force is the overall force acting on an object. It's the vector sum of all individual forces.

The Principle:

* If the net force acting on an object is zero, the object will either remain at rest (if it was initially at rest) or continue moving at a constant velocity (if it was already in motion). This means the object will maintain both a constant speed and a constant direction.

Examples:

* A book on a table: The book is at rest, and the net force acting on it is zero. Therefore, it stays at rest.

* A car moving at a constant speed on a straight road: The car is in motion, but if the net force is zero (meaning the forces of the engine, friction, and air resistance are balanced), it will continue moving at the same speed and direction.

Important Note: This law only applies if the net force is zero. If a non-zero net force acts on the object, it will cause the object to accelerate (change its speed or direction).