Okay, so imagine you have some toy cars that you really like because they're shiny and cool-looking. Well, the Soviet Union also liked shiny things, but instead of toy cars, they made shiny coins out of a special metal called platinum.
These platinum coins had pictures of important people and symbols on them, like their leaders and the hammer and sickle (which was a symbol of communism). People in the Soviet Union used them to buy things, kind of like how we use our own money.
However, platinum is a really valuable metal, so these coins were worth a lot more than regular coins. That means they were pretty rare, and not a lot of people could afford them. But they were still pretty neat to look at, even if you couldn't actually use them to buy anything.