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.
Language packs are about 200 MB in size, so they can be installed and uninstalled quickly. A single installed product can support several languages, enabling users to switch from one to another when required.