Under Configure tab > Language, you can choose the language of the interface labels and translate the course content into multiple languages using XLIFF export and import.
Here you can choose the language of the interface or add your custom translation.
In the All-in-One template, currently Afrikaans, Arabic, Bulgarian, Croatian, Czech, Chinese (Simplified), Chinese (Traditional), Danish, Dutch, English, Finnish, French, German, Greek, Hungarian, Indonesian, Italian, Japanese, Latvian, Lithuanian, Malaysian, Norwegian (Bokmål), Norwegian (Nynorsk), Polish, Portuguese, Romanian, Russian, Slovakian, Slovenian, Spanish, Swedish, Thai, Ukrainian and Vietnamese are available. More languages will be added soon.
All text items of the template interface (button texts, titles and headings, field names, error messages, validation messages, etc.) can be also translated into any other language.
To add your custom translation, in the language dropdown select Custom. In the Translation column, you can replace the default English texts with your own translations.
NOTE: Easily change the language of the authoring application under My Account settings. The supported languages are English, Dutch, German, French, Spanish, Ukrainian and Italian.