8 - Translate static content
Yes - you can do it hardcoded in twig, this can be translated via the user interface translation: /admin/config/regional/translate. The locale module needs to be enabled.


  BUT, i would only recommend this method for static content (and maybe random)!


For dynamic content i suggest to use the drupal multilingual feature(s). Start by enabling the module content_translation.
Then you can edit a node, and add a translation for it in the backend (node/x/edit). See the docs on d.o. for further information.