The Shipping tab will automatically be populated by the information you added within Production -> Shipping. In the picture below, you can see what we mean:
This is also another entry point to the Shipping section of the system where can you will add the vessels delivering your product. You can also remove any selected items by ticking the box beside the vessel and clicking the red Remove Selected box. It will be rare that you'll want to do that here. But be careful! Deleting a vessel from this list here will also delete the vessel from the whole system altogether.