Balanced and unbalanced forces
When the resultant (net) force on a body is zero, the forces on the body are said to be balanced.
There is no acceleration when the forces on a body are balanced. If the body is at rest it remains at rest. If the body is moving it will move with constant velocity.
A stationary trolley that is pushed by two people with the same force in opposite directions will not move as the forces are balanced.
When the net force on a body is non-zero, the forces on the body are said to be unbalanced.
There will be acceleration in the direction of the resultant force.
A plane that is pushed north by its engines and east by the wind will move northeast.