"en" is a pronoun meaning "de-quelque chose" and is used to replace something that was previously mentioned.
Verb "parler" is constructed with preposition "de" : "parler de" = talk about
In a conversation: - ton chien est stupide (your dog is stupid) - je le sais, alors pourquoi on en parle ? (I know that, so why are we talking about it?)
"en" means indeed "de quelque chose" with verb "parler". It can mean "à quelque part" with verb "aller".
The full construction of "aller" when you want to mean "leave" is reflexive:
- je m'en vais, tu t'en vas, il/elle/on s'en va, nous nous en allons, vous vous en allez (polite singular and plural), ils/elles s'en vont.
I'm kind of aggravated with the voice on this one. The pronunciation led me to write "Pourquoi un on parle?" which I knew didn't make any sense, but that's what it sounded like. If "on" had sounded like "on" and "en" had sounded like "en", I might have gotten this one right! Thanks for giving us a place to vent, DuoLingo. :)
This sentence is what makes it so much harder to listen to french for me. En and Un sound so similar to my ear to the extent that I was sure it was un even though the sentence didnt make much sense. (btw, I tried to write this paragraph in french but I had no idea how to translate the first sentence =( )
"On" is a different pronoun that means "we"
This might help: http://french.about.com/od/grammar/ss/subjectpronouns_5.htm
On is a third person singular form. Therefore the verb takes a third person singular form.
Il, Elle, On = third person singular. On refers to an undefined group. It is comparable to the formal use of one/we in English.
EG: One wants to be sure about the grammar. Note that the third person singular is used. In this example one is singular but means everyone. On is also singular and also means everyone.
The use of one as we is formal and uncommon in English. The use of on as we in French is informal and very common.