"I saw a really tall Klingon."
Translation:tlhIngan wochqu' vIlegh.
Do you know what a grammatical object is? You have a verb. The subject is whoever or whatever performs the verb. The object is whoever or whatever the verb is done to.
In Klingon, when the subject is jIH I and the verb prefix is jI-, it means there is no object. I'm doing the verb, but I'm not doing it to or on anything. jIlegh I see (no mention of what I see, so no object). When the verb prefix is vI-, it means the object is a third-person noun: a he, she, it, or they. Ordinary nouns are third person as well. tlhIngan vIlegh I see the Klingon. tlhIngan is third person, because it's a noun.
tlhIngan wochqu' is very tall Klingon. Noun phrases like this are still third person. tlhIngan wochqu' vIlegh I see the very tall Klingon.
jI- I (subject) — no object
vI- I (subject) — third-person object