The coupons were presented to the bond issuer by the bondholder to collect periodic interest payments.
The settlement date is the date the investor takes possession of a security.
Thefrequencyis the number of interest payments per year.Basisspecifies the method used to count days (see below).
To enter valid dates directly, you might use theDATE function.
Basis
Thebasisargument controls how days are counted.
The COUPNUM function allows 5 options (0-4) and defaults to zero, which specifies US 30/360basis.
Thisarticle on wikipediaprovides a detailed explanation of available conventions.