What do you mean by internal resistance of a cell ?

Explanation

The resistance offered by the electrolyte of a cell to the flow of current between its electrodes is called internal resistance of the cell.
An ideal battery has zero internal resistance and the potential difference across the battery equals to its emf. But a real battery is made of electrodes and electrolyte, there is resistance to the flow of charges within the battery. A freshly prepared cell has low internal resistance and it increases with ageing.