The word coupon, in finance, is use to denote the nominal value of a bond.
Example: If you buy a CHF 1000 bond with a 5% coupon, you will receive CHF 50 in annual yields. Returns are usually broken down into several payments per year. In this example, if your bond paid out coupon yields twice a year, you would receive two payments of CHF 25 every year.
In the past, paper securities included a section which served as a coupon. This could be cut out and exchanged for cash. Hence the term “coupon” referred to yields earned from bonds. Today, an increasing number of securities are stored electronically.