When you borrow money from a bank you will eventually need to repay the amount that you have borrowed. In addition to the amount that is borrowed the bank is likely to charge you fees and interest for lending you the money.
The interest rate that you are charge for borrowing the money is dependent on the product that you use and the banks perceived risk in lending to you. The greater the certainty the bank has that you will repay the money generally the lower the interest rate charged.