A Face Value of a bond is the value printed on the bond certificate. Even though the bond’s market price fluctuates all the time, the face value of the bond remains the same. At the end of the bond life (maturity date) the bond issuer redeems the bond at face value.
A Face Value of a coin is the legal monetary (in fiat money terms) value of that coin. For example 1 oz Canadian Maple Leaf Gold coin has a face value of $50 Canadian Dollars. Of course the market value of this coin is much higher.