Hello there, @Triangle Cap.
A Bank feed is a digital link between your bank account and QuickBooks Desktop. It is an online banking feature so you can download transactions and use other online services. Bank feeds also helps you avoid mistakes that can often be made when manually inputting lots of transaction data.
If you already recorded the transaction or cheque in QuickBooks Desktop, QuickBooks will match the downloaded transactions to any entries that are already in the related account.
You can check out this article for detailed information on adding, matching bank feed transactions: Add and match Bank Feed transactions in QuickBooks Desktop.
If you have other clarification, please don't hesitate to leave a comment below. I'll be glad to help you as soon as I can. Stay healthy and safe!