A creditor is a person or entity that is owed money. A debtor is the person who owes the money.
There are two types of debt: secured and unsecured. A secured debt is a debt where the creditor has an interest in collateral such that if the debtor does not pay, the creditor has the right to take some property of the debtor. Common examples include mortgages and car loans. When Jane does not make her car payments, the car creditor can repossess her car, sell it, and use the money from the sell to satisfy the debt.
Unsecured debt is a debt where the creditor is owed money, but if the debtor does not pay, there is no property of the debtor that can be taken. Common types of unsecured debt include credit cards and medical bills. If Jane does not make her credit card payments, she could eventually be sued by the credit card company, but the creditor cannot take the goods she bought with the credit card.