The default language is based on the language of your local machine, of course only when we have this language available. If not, it will be in English. For now, SpinOffice is available in English, French, Italian, Dutch, Danish, Russian, Romanian, German and Turkish.
After you logged in you are able to adjust the language via menu option Administration -> CRM preferences -> General -> Display language.
Please note that adjusting the language applies to all users in the database!