Alright, kiddo, imagine you have a big piggy bank. Modern Monetary Theory (MMT) is kinda like that piggy bank.
Now, usually, people think that the government can only spend the money it collects in taxes, just like you can only spend the money you save in your piggy bank. But MMT says something different. It says the government can create more money whenever it needs to, kinda like magic! But, just like with your piggy bank, there are rules.
MMT says the government can keep spending as long as it doesn't cause too much inflation. Inflation is like when the prices of things go up too fast, so your pocket money doesn't buy as much candy anymore.
So, in simple words, Modern Monetary Theory is like saying the government has a special piggy bank where it can make more money, but it has to be careful not to make too much or everything will get too expensive.