This simply means that balanced forces, acting on the same object, will have no effect on the motion of an object.
In practice this means:
The forces acting on this car are balanced.
The thrust from the engine is equal and opposite to the drag caused by air resistance and friction between the road and car tyres.
There is no resultant (or net) force as the forces add up to zero.
The car will continue to travel forward with a speed of 20 m/s in a straight line.
The upward force equals the downward force and they both act on the car.
The car remains at rest. It does not move upwards or downwards.
Balanced forces have no effect on an object.
If it is at rest, it remains at rest.
If it is moving at constant speed in a straight line, it continues to move at the same speed in the same straight line.