About Language Packs
Each Autodesk product is installed with a default language. A language pack is a mechanism used by some Autodesk products to provide another language for the user interface and the documentation. Each language pack contains only the text strings and documents required to support a user working in the specified language; it does not duplicate the core product software.
To run Navisworks in another of the installed languages, you need to add one of the language selector arguments to the desktop shortcut. Language packs are installed automatically during the Navisworks installation process, enabling users to switch from one to another when required.