There is nothing like an “n-space” in word processing. At best, or at worst, “n-Space” is “an American video game developer”. See n-Space
What it might be though is a typographic “en”, i.e. an “EN SPACE” (Unicode U+2002).
It might also be any of the multiple ways to code spaces through Unicode. Have a look at Unicode spaces
But in the end, it might be something else that Word chose to render in that way…
The only way you might be able to get rid of these characters all at once is through the “Ctrl+H” dialog, provided you can enter (copy/paste?) the appropriate code into the Find What box…