Your question was not clear. I’m assuming when you say “key words” to the right of “Word” are missing – that you are referring to the Word main menu. Just to cover the basics, on a Mac, unlike a PC, the main menu changes based on the active application. I’m also assuming that you have Word as the active window and that’s not the problem.
You may wish to consider reinstalling the Office application. There are a few things you should ask yourself:
1) Is this happening in all the Office applications – or just Word?
2) Did you make any system changes prior to this problem? (Installed new apps, changed settings, etc.)
3) Did you change the Office preferences?