If you have Selfnamed shipping profiles enabled (automatically on V3 or manually on V1), customers trying to order to destinations outside the EU, UK, or US will see: "Sorry, our items are not currently available in your region" in the checkout. They won't be able to place an order.
If you're using your own shipping profiles instead of Selfnamed's, and you accept orders worldwide, orders from unsupported regions won't sync to Selfnamed since we currently only ship to the EU, UK, and US.