On the last version of Joomla 3, each link, module, and article could be associated with a language.
I installed a new language from AdminCP (Joomla 3 has an integrated install language on administrator). Now when I create an article, I continue to see only English options for language, and not the new language I just installed
What is missing? Is it necessary to install a component?
I think Joomla 3 don't need a component like joomfish, because the content can be multi-language as a native feature.
You need to add the language you installed as a content language in the language manager.