The electrode on the left is the anode, where oxidation takes place, and the electrode on the right is the cathode, where reduction takes place.
The cell depicted is a voltaic cell.
A voltaic cell generates electrical energy by a chemical reaction that occurs spontaneously.
The anode undergoes oxidation, while the cathode undergoes reduction.
Therefore the electrode on the left is the anode, where oxidation takes place, and the electrode on the right is the cathode, where reduction takes place.