The word "debt" refers to money that is borrowed and must be repaid. Notice that this word is spelled with a "b," but the "b" is silent. The sentences below show how to use "debt" as a noun:
Roger has a large amount of debt.
Right now Chandra and Tim have very little debt. (They don’t use their credit cards very often and they pay for almost everything with cash.)
Some people are afraid of taking on too much debt.
A mortgage on a house is a very common form of debt in the United States.
Managing credit and debt is an important part of running a small business.
The national debt for the United States is trillions and trillions of dollars.
We owe a debt of gratitude to the firefighters who prevented our house from burning down. (debt of gratitude = this expression is used when someone does something for you for which you are grateful)