English is the only language support that is shipped with version 6.5+. Other languages are supported via language packs (a.k.a. Wordlets), which you either create or download.
Use the Languages link in the CP to see & work with the language packs that you have installed.
You can get a partial Spanish translation language pack at the
Trading Post. It's only a partial translation, but it's a start. <img src="https://www.ubbcentral.com/boards/images/graemlins/smile.gif" alt="" />