Sadly, it's not a correct translation, at least punctuated thus. You might say "Why! The wall is purple!" meaning good heavens, what a surprise, the wall is purple when I expected it to be white. But "why the wall is purple" is not a grammatical sentence is English. And I've been a native speaker since before the Flood.
May 24, 2020: This guy speaks so fast! I played it the "normal" speed multiple times and still don't hear "il" in the sentence until i change the speed to slow. Is this how Italian's speak normally where they speak so fast it sounds like certain words blend together, or are totally removed from a sentence?