This is displayed so that you can specify the appropriate delivery address when you make purchases on My Nintendo Store.
Please select the country that matches your delivery address. You must select the country that is registered as the "Country/region of residence" for your Nintendo Account.
If you select a country other than the registered country, it will be displayed as an invalid country. You can view the My Nintendo Store even if it is for a different country than the country configured in your country settings, but you will not be able to complete an order. When you go to select a shipping address for an order, only addresses in the country of the store that is selected will be displayed.
To change the "Country/region of residence" for your Nintendo Account, go here.
If you select "Nintendo Australia," the currency displayed will be Australian dollars. If you select "Nintendo New Zealand," the currency displayed will be New Zealand dollars.