A loan is like when you borrow a toy from your friend. You promise to take care of it and give it back after some time. Your friend trusts you and lets you play with the toy, but they expect it back in the same condition. Just like that, when someone gives you money as a loan, you promise to return it after using it for a while.
Think of a loan as a magic box that gives you what you need now, but you have to fill it back up later. If you borrow crayons from a friend, you can color your picture right away, but you need to return those crayons. Similarly, a loan gives you money to buy things now, but you have to return the money to the bank or the person who lent it to you.
Imagine a storybook where you borrow a character for your own story. You can use the character to make your story exciting, but you have to return the character to the original book. A loan is like borrowing that character, where you have to give back what you borrowed, sometimes even with a little extra, called interest, like adding a new twist to the story before returning it.