If you see a red exclamation mark❗️under the column Items in Label Creator > To Ship, it means that the order contains two articles or more.
Inside the order, there could be two articles with the same SKU. In this case, you'll also see the red exclamation point also next to Quantity:
If the order contains two (or more) different articles, you'll see all of them under the column Order ID:
Done! 🎈