Global settings
To set a default language for every discussion on your site, choose a language in your Disqus Admin > Setup > Appearance.
Language overrides
Using the this.language JavaScript variable, you can dynamically load the Disqus embed in different languages on a per-page basis. For example, to load the embed in Russian:
var disqus_config = function () {
this.language = "ru";
};For a full list of language codes, see Languages on Transifex. Note however that Disqus does not support all languages offered in Transifex. For a full list of supported languages, see the Disqus project on Transifex.
Comment counts
Comment count strings must be translated manually in your Disqus Admin > Settings > Community under Comment Count Link. This can only be applied globally across your site.
Best Practices
Avoid letting the user pick the language for the discussion. In most cases, letting users who speak different languages comment in the same discussion degrades the relevance of the conversation for everyone.
Unless your moderators are multi-lingual, it's usually better to create separate forums for each language. Otherwise it's more difficult to split moderation duties by language if multiple languages are used in the same forum.
If using multiple languages on a single forum, consider removing the text from comment counts entirely and overlaying the number over a comment symbol.