Issue & Receipt for Production mainly use in Production Process.
1.Issue For Production : Suppose you have manufacture Bike or its Engine In this case Bike/Engine is your Final Product.
For this you need raw material So after processing on this Final product will produce.In Sap Business One we need to Issue this Raw Material from its particular warehouse Location.that is Issue for production Process.
2.Receipt from Production :After processing on Raw Materials Final Product is Received.So it need to be receive on its particular warehouse Location as it is.
In above Processes Raw Material Get Consumed means Raw Materials In Stock Qty get Less.&
Finish Goods In stock Qty get Raised.
Also please find this Link it may Help you to understand these processes in detailed.