To enable the multilingual UI, install the relevant language packs which are available for Windows Server 2008 R2 , Windows Server 2008 R2 SP1, and for Windows Server 2008. See the screen shot below.
After the right language is downloaded, just run the executable and the language pack will be installed. ( See the screen shot below.)
Once it’s installed, you can change the language through the Keyboards and Languages tab of the Region and Language control panel applet. ( See the screen shot below.) A logoff is required to make the language change take effect.