Well, imagine you have a piggy bank at home where you keep all your money safe. But you don't want anyone else to know how much money you have in there or what you spend it on, right?
That's exactly what a numbered bank account is - a way for wealthy people to keep their money safe and private.
Normally, when you open a bank account, you use your name and ID to open it, right? But in a numbered bank account, instead of using your real name, you get assigned a number.
So, nobody knows who you are, except the bank who gave you that number. That way, if anyone is trying to spy on you or steal from you, they won't know where your money is kept.
This kind of bank account is often used by people who have a lot of money to protect, like celebrities, politicians or people with lots of wealth.
But, even though it's a good way to keep your money private, you still have to follow the law and pay taxes on your money, just like any regular bank account.