ISteamApps

Function Reference

apps.getCurrentGameLanguage()
returns:

(string) The language that the user has set.

SteamWorks:

GetCurrentGameLanguage

Gets the current language that the user has set. This falls back to the Steam UI language if the user hasn’t explicitly picked a language for the title.

For the full list of languages see Supported Languages

Example:

print("The games current language is " .. Steam.apps.getCurrentGameLanguage())