"I see only three Klingons."
Translation:wej tlhInganpu' neH vIlegh.
It can go after a verb, in which case it trivializes the action of the verb as with "merely, only, just.". But in this case, it should follow the noun where it means "only this thing and nothing more". The meaning is very similar, but the question is, do I merely see them (in which case it should follow the verb) or do I see only them (in which case it should follow the noun).
This is a tricky sentence. The neH follows tlhInganpu', so the sentence means I see three Klingons, not someone else like Romulans or Ferengi and not I see three Klingons, no more, no less.
It's unclear whether you could put neH after the wej to mean only three. I think you can since numbers generally act like nouns. If you can then wej neH tlhInganpu' vIlegh would be the way to say I see three Klingons, no more, no less.