When we use the <language> tag, it will show in the page but how to make it show in the sidebar menu ?
Topic on Extension talk:Translate
No, it’s not blocked. This feature has been ready for years; it’s blocked only on Wikimedia sites because of our interwiki language links. Third-party wikis (like translatewiki.net) can already use it by setting $wgPageTranslationLanguageList to 'sidebar-only', 'sidebar-fallback' or 'sidebar-always'.