Language packs contain third-party translations of the VeraCrypt user interface texts. Note that language packs are currently supported only by the Windows version of VeraCrypt.
Since version 1.0e, all language packs are included in the VeraCrypt Windows installer and they can be found in VeraCrypt installation directory. To select a new language, run VeraCrypt, select Settings -> Language, then select your language and click OK.
To revert to English, select Settings -> Language. Then select English and click OK.
You can still download an archive containing all language packs for the latest version (1.22) from the following link.