I gather you're asking about QuickBooks Online, however, I can tell you a little bit about the Accoutant's Copy in QuickBooks Desktop.
This feature allows you to create a separate file to provide to your accountant while allowing you to work in your file at the same time. The two can be merged later when your accountant completes the review. You have control of the date range in which the accountant can make changes such as General Journal Entries and bank account reconciliations. QuickBooks has designed this feature to be safe as highlighted fields appear in transactions that will be sent back to the client. However, one added benefit the Desktop version has is the ability to make backups before incorporating any changes.
For greater details about what can and cannot be done with the Accountant's Copy, please see the Overview.