Review what a content type is and how to display content in different methods.
Review how to use display modes across multiple content types.
Review how taxonomy can organize content.
Review how blocks in Drupal 8 are fieldable and can be placed in multiple different regions instead of only one region.
Review how to enable menus on content types.
Review contextual filters and display settings in the view ui.
Research where in the admin interface you can export configuration.
Review how to start a site with a new default language. Review how to configure multilingual entities. Review Twig multilingual manipulation.
Review the GET method and the correct way to retrieve a GET response.