Chart of Accounts
For each account, both in the list and in the card, a preview is available showing how many items of the Balance and Profit And Loss Statement it has been used for. The displayed number is the sum from all available batches, and in the case of the balance sheet, additionally the sum of liabilities and assets.

By clicking on the field, you will be taken to the calculation settings page with a list of filtered positions. If you want to see a specific line directly in the corresponding report, you need to use one of the two actions:
Show line in Balance,
Show line in Profit&Loss Statement.