What it is:
In the finance world, a note is debt.
How it works (Example):
You might hear people use the phrase "carry the note," which means to take on debt from another issuer. For example, let's say you plan to purchase a business for $2 million. You have only $200,000 in cash for the seller and want to pay the seller over time for the rest. Essentially, you're borrowing $1.8 million from the seller, and the seller is "carrying a note" until you pay back that $1.8 million.