ELI5: Explain Like I'm 5

Foreign-exchange reserves

Foreign-exchange reserves are like a special bank account that a country can use in order to pay for things if it doesn't have enough money. Countries keep this bank account full of money so they always have enough to buy the things they need. They usually keep it full of different types of money from all over the world which means that if they need to buy things in other countries, they can use the right money.