Default Template
From Posstack.com Documentation
Within the context of the Easy Content Builder, default templates refer to the default JSON template files of products (product.json), pages (page.json), and articles (article.json) in your theme. JSON templates are a collection of sections that are configured to give your Shopify store a consistent look and feel.
In the theme editor, you can discover which templates are applied to which pages, and then edit them to customize the information displayed to your customers.