Duo rejected "Man has two feet", stating that "You need the article 'The' here."
So I then tried the synonymous "Man is bipedal" - which Duo rejected in favour of the far less general "This man has two feet."
But this sentence isn't general. It's about "this man". Sure, most other men also have two feet, but the sentence is just about one ;)
Ten mezczyzna ma dwie lewe stopy (In English "This man has two left feet" usually means he's a really bad dancer. Is it used this way in Polish?
"dwie lewe ręce" (two left arms/hands) is common in Polish, but I don't remember hearing "dwie lewe stopy". I googled it, it has 744 results. Well, even if it isn't a saying, it would be understood thanks to the analogy.
I googled "dwie lewe nogi" (two left legs), and this one has 25500 results.