The Bills feature is available in the Sales Pack extension.
A bill is a document that represents an invoice received from a supplier and records purchased products or services, including their quantities, prices, and the total amount payable.
A bill can be generated from an existing purchase order, carrying over its line items and details.
A bill’s outstanding amount can be settled through the allocation of outbound payments or bill credits.
Bill credits
Bill credits document accounts payable reversals, typically originating from supplier credit notes. They can also be used to reverse incorrectly issued bills.
Documentation
For more detail information on using Sales Orders, see the documentation.