The term 'Cambodian Coin' refers to the official currency of Cambodia, which is the Sen and the Riel. The Sen is a three-letter currency, while the Riel is a four-letter currency. The Sen was introduced in 1953 and is divided into 100 equal parts, while the Riel was introduced in 1980 and is divided into 10 equal parts. Both currencies are used in Cambodia, with the Sen being the primary currency and the Riel being the secondary currency.