Newton's First Law of Motion is all about <em>"Inertia." </em>It states that every object will remain in its state of rest or motion unless a force compels it to change its current state. This force is known as "unbalanced force," a force which causes an object to accelerate.
For example, a ball will remain on the floor <em>(at rest)</em> unless somebody kicks the ball. The force of the kick is considered the "unbalanced force" because it made the ball move.
Newton's first law says that an object that is not moving or is at <u>rest</u> will stay at <u>rest</u> an object that is moving will keep moving with a constant <u>velocity</u> which means at the same <u>speed</u> and in the same <u>direction</u> unless an <u>unbalanced</u> force acts on the object.