Here's a breakdown:

* Force: A push or pull that can cause a change in motion.

* Net Force: The overall force acting on an object, calculated by adding up all the individual forces (considering direction).

* Zero Net Force: When all forces acting on an object balance each other out, resulting in no change in motion.

* Non-Zero Net Force: When the forces acting on an object don't cancel each other out, resulting in a change in the object's motion (acceleration).

Example:

Imagine pushing a box across the floor. You are applying a force in one direction, but friction is acting in the opposite direction. If your force is stronger than friction, there's a net force in the direction you're pushing, and the box will accelerate.