Purpose of Stock Received but not Billed
When purchased items are received, an accounts posting is done based on the value of the purchased items in the Stock-in-hand / fixed-assets account. When you sell and deliver those items, an expense (cost-of-goods-sold) is booked, equal to the buying cost of the items.
As stock balance increases through Purchase Receipt, Warehouse account is debited and an adjustment account called Stock Received But Not Billed account is credited. At the same time, the negative expense is booked in account head having category as \