Electric potential on one side of the closed circuit is applied and this causes the electrons to move to a position of lower potential. Imagine this as when you raise an object above the ground and release it. It moves from its higher potential energy position above the ground to its lower potential energy position.
When the potential difference is provided to the conductor then the electrons start moving in the conductor. The electrons move from lower potential to the higher potential.
The rate of flow electrons constitutes the electric current. The direction of the electric current is opposite to the direction of the electrons.
For example, suppose the battery is connected to the circuit. It forces the electrons to flow in the conductor. The battery provides potential to the electrons so that the electrons can flow in the circuit. There are two terminals in the battery: Positive terminal and Negative terminal. Positive terminal is at higher potential. Negative terminal is at lower potential.
In this way, electrons flow in the circuit and constitute the electric current flow in the circuit.
