Clicking on Listings -> Listings menu at the left menu bar or Listings in the middle of dashboard page take you to the linked listings page.
This will show current list of all linked listings. These are the listings linked between Etsy and Shopify via the app.
Sync Request
The app always keeps the list of Etsy products up to date. But in case you think something is missing, you can click on the Import Products button on this page to import all Etsy products in the app.