Net profit is like when you get a bunch of toys and you sell some of them at a price. But before you can say, "Yay! I made some money!" you have to think about all the costs you had to pay to get those toys. You had to pay for the toys, pay for the place to sell them, and pay for the people who helped you sell them.
So, net profit is what you have left over after you subtract all those costs from the money you made selling the toys. It's like counting how much money you have in your piggy bank after you take out the money you spend on candy and toys.
If the net profit is a big number, you can celebrate because that means you made a lot of money. But if it's a small number or even a negative number, that means you didn't make very much money, and you might need to think of ways to make more profit in the future.