Goods Issue 
The goods issue function lets you reduce the inventory level in a situation that is not direct result of a sales document entry.
After an item is sold, the warehouse inventory is automatically reduced when SAP Business One enters the transactions. For example, if you create a delivery document that is based on a sales order, the warehouse inventory is reduced by the specified quantity once the delivery document is added.
However, the sale of an item is not the only type of transaction that results in a goods issue.
Example
For example, if five units of an item suffer water damage in a warehouse, they cannot be sold and are removed. In such a case, you can post a separate goods issue using the function described here.
End of the example.