Setting a Preferred Language
You can set Tableau to display the user interface (menus, messages, etc.) in one of the supported languages. The language you select is your User Interface (UI) Language. By default, when you install Tableau, the language is set to an automatic setting that recognizes your Windows Locale and uses the appropriate language if it is supported. If you are using an unsupported language, the application will default to English.
To change language:
Select Help > Choose Language.
Restart Tableau Reader.
Note: A workbook author can set the language (locale) for a workbook, which determines how numbers, dates, map tiles, and so on are displayed. In that case, the language setting in the workbook takes precedence over the language that you've set for Tableau Reader.