Hello,
Thanks for reaching out here in the Community.
In QuickBooks Online, you use accounts to track your bank and credit card transactions. These accounts need to match the real-life accounts you're tracking. When you first create accounts in QuickBooks, you'll enter the current balance of your real-life accounts. This is known as the opening balance.
To learn how to enter an opening balance in QuickBooks Online, take a look at this article: Enter opening balances for accounts in QuickBooks Online.
If you have any other questions after reading that article, please don't hesitate to reach back out in the comments section below.
Have a great day!