The verb “parler” is indeed supposed to be unconjugated. That’s down to differing grammar and syntax in French and English. If I were to try and translate directly from French to English while maintaining the original sentence structure and whatnot, it would look roughly like this: “I not know not speaking French.”

…Which is awkward as hell to read, mostly thanks to French splitting negatives into two parts, but you can see how the verb “parler” (speaking or talking) is unconjugated.

You may also notice how that sentence structure looks more similar to an antiquated way of speaking English, if we tweak that just a little bit: “I know not how to speak French.”