This feature allows you to review and Approve Invoices for all EHID's that you have access to on the same page, without having to select each EHID from the dropdown.
By clicking the +EHID button on the Invoice Approval page, the list of EHID's for which the user has access will be displayed. The invoices of all the EHID's that you select and add would be displayed on the page.
You can approve invoices for the selected EHID's all at once.