Language of Parts in TinyMCE

This allows you to mark a part of a text as "other language": the "lang" attribute is supplemented. It is useful for search engines or screen readers to customize the language or pronunciation.

In the TinyMCE plugin you can define the languages you are using in your texts.

If you want to make it easy for editors, then pull the language icon to the allowed icons for your editors. Otherwise they need to select a language with the format button and scroll down there.