The Finalise button is available in all modules that contain transactions that do not require shipment or invoicing, and works the same way in every module.
Finalising a transaction completes and posts the original transaction, creates an open item, and posts the open item to the General Ledger.
When you click on the action button of Finalise on any transaction, the status of that transaction = Posted.
The example below shows how the Finalise button is used to finalise a customer payment:
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