Starting with Arc v1.4.1, Arc supports now English, Spanish, German and French. Arc will display the language defined in your web browser settings.
If you are using Chrome, you can filter Chrome’s settings to show only settings related to “language”, the language used by Arc will the first one in the list. In the example below Arc will display English:
To use the French language instead, just move French to the top of the list:
You then just need to refresh Arc and it will now display the new language:
All other languages than German, Spanish and French will display in English.