Online Documentation for SQL Management Studio for SQL Server
If you did not select the program interface language when you started SQL Management Studio for SQL Server for the first time, or you have decided to change the language settings, use the Options | Localization main menu item.
The Localization section of the Options dialog is provided for managing the localization files of SQL Management Studio for SQL Server.
You can create your own *.lng files similar to those available in the %program_directory%\Studio\Languages folder, add them to the list of available languages and set the new language as the program interface language.
Lists all the languages available for localization and the corresponding *.lng files.
Specify the directory where the *.lng files are stored by default.
This button is used for searching for *.lng files in the Language Directory and adds all of them to the list.