A language pack consists of different informations you need to work within a language.
The display language of Windows in example contains resources with all text elements of Windows dialogs, menus, output, and error messages, and tool tips.
Another important thing you need is the keyboard layout for the desired language. Depending of a language the keys on a keyboard have different characters printed on. Some languages have in example umlaut characters, like ä,ö,ü in German, Turkish, and Finish. Or accents, like in é, à , î, and ô (and more) in French, and their is a whole bench of other characters in other Northern Europe languages. Naturally this language feature is not limited to European languages.
But even if the characters which two languages or regions are using are identical, they may be used in a different order. Especially numbers, brackets, punctuations, and currency symbols may be on different keys.
Don’t trust my word. Give it a try. Visit an internet café or a PC in a hotel lobby, on your next travel into another country. Typing such simple thing as an email may be very challenging. 😉
A Windows language pack also includes sets of regional settings for Clock, Currency, number formats, and more.
Depending on the language, it may also contain fonts, or special character entry tools, like Microsoft IME for Japanese or Microsoft  Pinyin SimpleFast for Chinese.
More things to read
- How to install a language pack in Windows 8?
Hope this helps. Just let me know, and leave a comment.
Renate
