Question

explain how does a cell maintain current on a circuit

Answer 1

When the cell is connected to a conducting circuit element, the potential difference sets the charges in motion in the conductor and produces an electric current. In order to maintain the current in a given electric circuit, the cell has to expend its chemical energy stored in it.

Answer 2

If by cells, you mean a battery, then it provides a potential difference in the circuit connected across its terminals enabling the flow of current in the circuit. ... The circuit enables a discharge path that can be used to power devices,etc.