Comma-separated list of languages. Vim will use the first language for which the desired help can be found. The English help will always be used as a last resort. You can add "en" to prefer English over another language, but that will only find tags that exist in that language and not in the English help. Example:

:set helplang=de,it

This will first search German, then Italian and finally English help files. When using CTRL-] and ":help!" in a non-English help file Vim will try to find the tag in the current language before using this option. See help-translated.

(default: messages language or empty)

only available when compiled with the +multi_lang feature