If the resultant force on a stationary object is zero, the object will remain stationary. If the resultant force on a moving object is zero, it'll just carry on moving at the same velocity.
What does this mean?
If something is moving at a constant velocity
The resistive and driving forces must all be balanced
The velocity will only change if there's a non zero resultant force acting on it
What will a non-zero resultant force always produce?
acceleration or deceleration in the direction of force
Inertia
The tendency of objects to continue in their state of rest or of uniform motion
