You'll enter the current balance of your account, accounts.
When you select a date, you enter the account balance of that day from the bank statement. This is to make sure the opening balance in QuickBooks matches with your bank records.
If it's a deposit account, enter positive balance. Negative balance for expense.
You can check out these articles to help you organise your accounts:
Drop a comment below if you have other questions on how to handle accounts in QuickBooks.