TSRef - TypoScript Reference
4.1.6. language
Syntax:
[language = lang1, lang2, ...]
Comparison:
The values must be a straight match with the value of getenv("HTTP_ACCEPT_LANGUAGE") from PHP. Alternatively, if the value is wrapped in "*" (eg. "*en-us*") then it will split all languages found in the HTTP_ACCEPT_LANGUAGE string and try to match the value with any of those parts of the string. Such a string normally looks like "de,en-us;q=0.7,en;q=0.3" and "*en-us*" would match with this string.