by Fahad Alduraibi on WordPress.org
This plugin allows the user to set the blog language per post or page while having a default blog language.

The settings page of the plugin where you add needed languages.
Do you write posts in different languages?
Would you like your blog theme language to be the same as the language in which your wrote your post or page?
With this plugin you can set the language of your blog per post and also per page, that is if your blog is in English and you wrote a post or a page in Spanish or Arabic you can set the language of your blog to match that post’s or page’s language, so when your visitors open that post or page they will see your blog in that language. You don’t have to translate your theme and plugins if they come with translations and even it will change the direction of the view to RTL (Right-to-Left) if your language is RTL based.