The Prepare For Accounting action is used for transactions to update transaction amounts.
When line items are added to any action, the total amount is not immediately calculated until a Save All action.
However, if you want to calculate and update the transaction before doing a Save All action, you would use the Prepare for Accounting action.
▶ Select a table: the table with the transaction to update.
▶ Prepare records where: the criteria assumes the transaction's Record ID is stored in the Screen Active Record ID and sets this by default.
▶ Attempt to sync this record with my accounting software: As stated, it attempts a sync to QuickBooks.