In QuickBooks Online (QBO)'s Banking page, "In QuickBooks" means it's the total balance of the bank transactions you’ve added or matched in the system. While the "Bank Balance" is your bank's actual balance from the last bank feed update.
Once your spending account's transactions are downloaded, you'll have to review and match them to the existing entries in QuickBooks. This is to make sure you're able to assign them to the appropriate accounts and keep your books accurate. For the step-by-step guide, kindly refer to this article: Categorize and match online bank transactions. It includes details about excluding personal or duplicate ones.
Additionally, I'd recommend reconciling your spending account every month. This is to effectively monitor the growth of your business along with your income and expenses. You can refer to this article for the detailed steps: Reconcile an account in QuickBooks Online. It also contains instructions about editing completed reconciliations.
Please know that you're always welcome to comment below if you have other concerns or follow-up inquiries about the banking feature in QBO. I'm just around to help. Take care always.