Okay, so imagine you borrow a toy from your friend but forget to return it. Your friend may remind you a few times to give it back, but if you still don't remember or don't want to give it back, your friend might get upset and ask someone else to help them get the toy back. That person is like a collection agency.
A collection agency is a company that other companies or individuals hire to help them collect money or items that someone else owes them. For example, if you borrow money from a bank and don't pay it back, the bank may hire a collection agency to contact you and try to get you to pay them.
The collection agency will usually try to contact you by phone, email, or letter to ask for the money or item you owe. They may also try to negotiate a payment plan with you if you can't afford to pay all at once.
If the collection agency is unsuccessful in collecting the debt, they may take legal action against you, such as filing a lawsuit. This is why it's important to pay back what you owe and to communicate with the collection agency if you're having trouble doing so.
So just like how you should always return borrowed items to your friends, it's important to pay back any money or items you owe to other people or companies so you don't have to deal with a collection agency.