Okay kiddo, so there was this place called the Soviet Union, and a long time ago, around the 1920s, the people who ruled over it, the government, decided to print lots and lots of money. They did this because they wanted to pay for big projects and programs, like building new factories and farms.
Now, why is this a problem? Well, think of it like this: if each of your toys was worth one dollar, and suddenly there were a lot more dollars in the world, then your toys wouldn't be as valuable anymore. In the same way, when there's a lot of money in an economy, like in the Soviet Union at the time, the value of the money starts to fall, and prices for things like food and clothing start to go up really quickly.
This is called inflation, and it can be bad for lots of reasons. People might have to spend more and more money to buy the things they need, and their paychecks might not keep up with the rising prices. Plus, since the money is worth less, people might start to lose faith in it, and it gets harder to trade with other countries.
So, back to the Soviet Union: the government kept printing more and more money, but the prices for things like bread and shoes and toys just kept going up and up. This is called hyperinflation, and it can be really dangerous. People might stop trusting the banks, or they might start hoarding goods like food and medicine, because they're worried they won't be able to buy them later.
In the early years of the Soviet Union, hyperinflation was a big problem, and it made life really difficult for a lot of people. But eventually, the government was able to stabilize the economy and bring inflation down to more manageable levels.