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.