Welcome to the home page of your neon application. This file is /themes/default/pages/home.tpl and it extends the /theme/default/layouts/layout.tpl file.
Cobe cms has rendered this page for you because there are entries in the database tables cms_page and cms_url the home page is defined by the url of '/'. These were created from the migration /apps/main/migrations/m20200101_000000_main_create_home_page.php during the installation of this project. Cobe renders any pages or partials defined in these tables and stored in the themes directories automatically.
Understand how this works, and then you can have fun creating your neon application.