The first step in enabling a project to support localizable resx files involves modification to your project’s properties.
Enabling a project to support a particular culture has been made easier with the Windows Phone 8 SDK. No longer is it necessary to edit your app’s project file in a text editor.
Select the project node in the Visual Studio Solution Explorer and press ALT+Enter. Then use the Supported Cultures section in the Application tab to select the languages that you intend to support.
Compiling your project with culturally specific resx files produces independent satellite assemblies located together within the resulting XAP file.