The coin is from France.
It doesn't have a date on it, but it was struck during the reign of French king
Francis I (his name in French is "François I"), who reigned from 1515 to 1547.
The coin is "silver" (that's what the "AR" means; fineness unspecified). The denomination has the rather lengthy name of "douzaine à la croisette" which translates to "a douzain (dozen) with a cross on it", so called because there were 12 deniers to a douzain.
"Ciani" is a French Kingdom coin catalogue reference, their equivalent of the US
RedBook or the British Spink for the pre-Revolutionary period.
One thing the flip seems to neglect to mention is the mintmark: I can see the letter "M" on both sides. I believe this is the mintmark for Toulouse.
There isn't a 1500s Krause catalogue yet, and I don't have Ciani or any other catalogue giving values for coins of this period, so I don;t know what a book value might be.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis