If you are unfamiliar with ancestor money it looks kind of like toy money. You can tell it's not "real" of course but it still has the elements of spendable currency.
The idea of producing it was to supplement "real" money to give to deceased loved ones. The concept was that the passed on family members can use this "money" in the afterlife to get things they need.
So, what is ancestor money, again? It's a tool that allows us to take care of our ancestors, in return, they take care of us. It is natural for people to look out for others that have their best interest. Giving offerings and ancestor money makes you someone that the ancestors look at as a CARETAKER. Therefore, they'll take TAKE CARE of you!