Packing slips are lists that indicate details about all items shipped in a single shipment. For orders that ship more than one shipment, you can generate different packing slips for each shipment.

Step 1: Click on Orders from the Shopify store.

Step 2: After that select Order and click more actions > Print packing slips.

Then you can download the Pdf file of all your selected orders.

If you want to edit the packing slip template then click settings>Shipping and delivery and edit the packing slip.