"Left" means: already, finished, finished, etc. Generally used to indicate that something is over. For example, "after dinner" can be said to be "left-handed" and "stupid" can be said to be "stupid left";

"Baa" means "horse" and is usually used only after "Xi". For example, "is it" when "Xie"; "Yeah" and "what" are exactly the same, it goes without saying!