Text for UI elements are grouped together as a set of translation keys in _data/locale.yml, this make TeXt easy to support different languages.
titles, you can define multi-language name for page, layout and navigator title. TeXt default defined some multi-language name in _data/navigation, _layouts/archive, _layouts/home and about.md.
The translation keys and multi-language names mentioned above support the following languages:
|English||en, en-GB, en-US, en-CA, en-AU|
|Simplified Chinese||zh-Hans, zh, zh-CN, zh-SG|
|Traditional Chinese||zh-Hant, zh-TW, zh-HK|
|French||fr, fr-BE, fr-CA, fr-CH, fr-FR, fr-LU|
You can see examples for different languages HERE.