Coin French is a term used to describe two different types of coins. The first is the Sou, which is a French coin that was used from the Middle Ages until the 19th century. It was made of copper and had a value of one-twelfth of a livre. The second is the ECU, which stands for European Currency Unit. It was a unit of account used by the European Union from 1979 to 1998, and it was replaced by the Euro in 1999.