(Not a Teacher)
That's paper money, as opposed to hard currency like coins. More specifically, it's a substitute for legal tender. Since the Confederacy wasn't recognized by many governments (if any at all, my memory on the subject is a little hazy), it's currency didn't have much legitimacy outside of the Southern states, so it couldn't really be considered legal tender. The scrip was basically issued on the hopes it would be worth something once the Northern states made peace with the Confederacy, which could then establish formal diplomatic relations and conduct commerce normally.