Nice tin, and a good buy for someone.
The stamps are Belgian postage stamps. Looks like a stamp collector was storing stamps in the tin and stuck one to the outside as a label.
The extra bit at the bottom of each stamp is a label saying something like "do not deliver on Sunday". Yes, in the late 1800's many places delivered 7 days a week. And the label was a nod to the more devout letting the postman know not to bother them with mail delivery.
So now you know the rest of the story......Hope it helps the sale
Steve B