Happy feast day to Saint Joseph and to all the Josephs out there.
According to a source I found on the 'net, a bon point was a card given to a school child as a reward for some work well done. (The antique equivalent to a smiley sticker, perhaps.) It's printed on a sturdy piece of card stock - just right for a child.
The back offers an uplifting reminder:
"What God at one time touched, remains sanctified/
I think it really means: "What God touches at once, (it) remains hallowed/sanctified."*
*Thanks to Sandra for her translation skills.