In function of your function of Office, the way to change the language is not the same. If you have Office 2016, it’s very easy because it’s include in the interface of any Office application (like Excel 2016, Word 2016, …) and it’s free.
For the other version of Office (Office 2013, Office 2010 and Office 2007), you have to open a specific tool to change the language. But, before to use it, you have to download the pack language (links at the end of this page). But it’s not all. In function of your Office version, you can not use the same pack language. If you download the pack language for Office 2013 and you work with Office 2010, it won’t work.
If you have the latest version of Office, you can easily change the language of Office. Look at the following video to see how to proceed.
Other version of Office
Now, if you use Office 2013, Office 2010 or Office 2007, here is the way to change the language of your application. It’ not very difficult but before, you must have install the pack language that you want.
Download your Office pack language
Find in this list the pack language you want to download.
Warning : the pack language of Excel 2013 and Excel 2010 (and 2007) are different.