When all the forces are balanced, the resultant force is zero. In this case:
A stationary object remains stationary
A moving object keeps on moving at the same speed in the same direction
For example, in the diagram of the weightlifter, the resultant force on the bar is zero, so the bar does not move. Its weight acting downwards is balanced by the upward force provided by the weightlifter.
The longer the arrow, the bigger the force. In this diagram, the arrows are the same length, so we know they are the same size.