This song, the second in the show, is built around a pun. Peccato means “sin,” but the phrase Che peccato is used like the English “What a shame!”
The singers are Don Silvestro, the priest, and Clementina, the mayor’s daughter, who has a crush on him (which he, secretly, reciprocates) and goes daily to confess sins that she hasn’t actually committed, just to have an excuse to talk to him.
I’m a huge fan of musical theater, grew up singing along with The Music Man, Camelot and Oliver. The first show I saw on stage was You’re A Good Man, Charlie Brown, in what must have been a local or travelling production, in San Francisco, when we were on home leave in 1969. I knew all these shows by heart, and by now know (and have seen) many more – most recently, Spamalot.