Translation:Excuse me, are you speaking about the balcony or the chimney?
While technically "az erkélyről beszélek" could mean both about and from the balcony, this sentence structure would usually mean about. There would be other clues in the sentence to suggest speaking from the balcony rather than about, probably including the word for down. It wouldn't really work with "talk down" (lebeszél) though because that means "talk someone out of something" so I would translate your sentence as "Lekiabálok az erkélyről" - I shout down from the balcony. Isn't Hungarian a lovely language? :D