Hi,
What he means is that you will have a 2 phase liquid in your flask. the top is the aqueous layer, the bottom is dirty ketone. The ketone is more dense, that's why. You'll tap it off(drain it) until you only have the top aqueous layer in your funnel. Then you extract that layer with the DCM(pour in an aliquot[20ml] of dcm, shake, wait for separation, drain off bottom small layer of dcm/ketone, repeat 3 times).
Hope this helps. Remember that organic chemistry is a loose art when it comes to wording. Know your densities to know which layer is on the top or bottom in extractions. KNow what happens to your extracted product when you add base or acid. In short, pay attention, and learn your chemistry if you wish for sucess.
Good luck