When a document is ingested and language identification is enabled, its primary language is identified. DISCO currently supports eight languages (English, German, French, Portuguese, Spanish, Chinese, Japanese, and Korean). If a document has too few characters or is primarily in an unsupported language, the language will be identified as "undetermined".
A Primary Language column can be displayed by creating a custom column and selecting the Primary Language option under Metadata.
You can also search for documents based on language, using the primaryLanguage(Language) search string. See Searching in DISCO (best practices) for more information.