So, Wechselthaler is a word that means "exchange thaler" in German. Thaler was a type of silver coin that was used a long, long time ago in many different countries.
Imagine you and your friend both have toys that you don't want anymore. You might want to exchange toys with each other. Well, Wechselthaler was kind of like that! People used thaler coins to exchange goods and services with each other.
But sometimes, people needed more than just one thaler to get what they wanted. So, they would exchange their thalers with other people for something else or more thalers. This is where the "exchange" part of Wechselthaler comes in.
Wechselthaler were actually a type of paper money that was used in the 1800s. They were like big, fancy IOUs (that means "I owe you"). People would exchange their thalers for Wechselthaler paper, which they could use to buy things or exchange with other people for more thalers.
So, Wechselthaler were basically a way for people to exchange and buy things with paper money that was backed up by the value of thaler coins. Cool, right?