When using Drupal’s taxonomy system, we need to find a way to sync the terms that we create to keep the taxonomy selection limited to just the terms for a given language. We don’t want all of the different languages showing up at the same time when someone is looking at a vocabulary or individual terms on the site. We're going to work with taxonomy to create our site's forum. The Forum module’s containers and forums structure is built on Drupal’s core taxonomy, so it is also creating a new vocabulary on our site. The forums on our client’s site need to display the threads that follow the same content selection rule as the rest of the content on the site. That is, we’ll only show the forum posts for the selected language. The site will have preset containers and forums, and then users may post to them using whichever language they choose.
Check your version
This video covers a topic in Drupal 7 which may or may not be the version you're using. We're keeping this tutorial online as a courtesy to users of Drupal 7, but we consider it archived.