The most common acid fuel cell is the Phosporic Acid Fuel Cell . A standard solid polymer electrolyte is Nafion. The electrons go round the external circuit connected to the fuel cell, and reach the cathode.
Water is produced at the cathode.
The anode is the electrically negative terminal. Some people find this surprising, since they are wrongly taught that anode always means positive. The anode is also the correct name for the negative terminal of any primary cell.