The J rope pull is a kneeling exercise that takes better advantage of the lats than the classic pullover exercise used by many bodybuilders. Remember, the lat fibers don't run completely vertical, nor do they run completely horizontal. They actually run on a bit of a slanted pattern, and targeting them for isolation will require the arms to follow suit to effectively tap into this pattern.
The J rope pull combines scapular depression and scapular retraction by mixing a stiff-arm pulldown with a row motion in a graceful transition. These are cool as a finisher to really hit the upper lats and provide a finishing pump that many other exercises can miss.