This is an English content to demonstrate the difference between installed languages and content languages.
To make it very clear: this content is written in English and so English is the content language of this content. Even if you'd change Joomla!'s installed language to Spanish or French, this content's language would still be English. No, it will not translate itself to another language automatically.
Look around on this page: although this content is written in English, everything around this content, in particular Joomla!'s own messages, is still in written in the current installed language (should be German at the moment).