A credit rating agency is like a teacher that grades how good you are at paying back borrowed money (like a loan). It looks at past borrowing history, your work, your salary and other things to decide if you would be a good person to lend money to. If you have a good score from the credit rating agency, you will be able to get a loan with a lower interest rate or better terms. If you have a bad score, you might not be able to get a loan at all.