Okay kiddo, k-t-b stands for "know the balance". It's a way to make sure you don't spend more money than you have in your piggy bank or wallet.
Imagine you have some money in your piggy bank. If you want to buy a toy, you have to check how much money you have first. If you don't have enough money, you can't buy the toy. That's why it's important to k-t-b!
It's the same for grown-ups too. They have a bank account where they keep their money. Before they buy something, they need to check their balance to make sure they can afford it.
By k-t-b, you can avoid running out of money and getting into debt. It's important to keep track of your money, just like you keep track of your toys or games. So, always remember to k-t-b!