To enable this, create a smart collection named All Products and set the condition to 'Product price is greater than 0'. You can create a collection through the 'Collections' menu in Shopify admin. Or you can turn this section off through theme settings.
You will receive 5 identical postcard to share them with your friends, maybe to send them via postcrossing or private swaps.
Collectible postcard item - Books, memories, Documents and Family Photos