What current yield is measuring
Current yield takes annual coupon income and divides it by the bond's current market price. That makes it an income snapshot, not a full return measure. It answers the narrow question: how much coupon income does this price imply right now?
This distinction matters because bonds often trade away from face value. A bond with a 5% coupon does not necessarily deliver a 5% current yield if the market price is above or below par.