Hello,
We used a simple menu widget for the demo only http://prntscr.com/rk21v0 just to inform user that he could place switchers in that area. If you want to create the multilanguage site you need to use special plugins like WPML or Polylang or qTranslate or any similar and add special widgets that come with these plugins to header area
https://xstore.helpscoutdocs.com/article/31-translation-with-wpml
Here you can watch video tutorials about the header builder – https://www.youtube.com/watch?v=RbdKjQrFnO4&list=PLMqMSqDgPNmDu3kYqh-SAsfUqutW3ohlG
Regards