Basically, the meaning of this error your products must be deleted from Shopify and present in our App, and due to the unavailability of the same product on Shopify we are unable to create the order on Shopify.
To sync the order on your Shopify, Firstly you need to delete that product from the App and then create the product with the same product title in your Shopify Store for which the order has been placed (provide the same SKU as on Etsy) After creating the product you need to follow these steps to create the order on the Shopify store:
Case 1: When your auto-import setting is enabled that product must be auto-import in the App automatically,
Case 2: If you have disabled the setting of auto-import then you need to import that product forcefully in the App.