The software is allow to use a multiple languages in the interface. The special language variables are used for this purpose. User select the language by clicking the appropriate flag in the interface.
You are free to add a new language and translate the variables to it. For the translation the import/export can be used.
However some of the actual date, like user messages in the communication board cannot be translated. All of the fields, which can be translated are marked by the small red square near the field name.