In other words, it is a document used to register in Openbravo the specifics of items physically received in the warehouse.
Normally, the warehouse team is the one in charge of receiving the goods as well as the delivery notes attached to the goods.
That's the source of information to take into account while issuing Goods Receipts.
As described in the Costing Server article, the cost of a "Goods Receipt" is calculated based on the related purchase order price of the goods, excluding taxes.
The calculated cost of a "Goods Receipt" is used while posting it to the ledger.