I've got a question about a wooden sparring partner called a "mook jong?"?

I've heard that a mook jong has three short arms and one leg, what are those used for, I know their used to represent possible positions of an attacker's arm, but what kind of attack does the arm at stomach height represent. Also, the wooden man or dummy, mook jong, is usually supported by a frame or heavy base structure, a man made a mook jong by cultivating, trimming, and carving on of the trees in his yard. I understand carving and trimming, but why cultivating, what does that even mean and even more, I've heard that it means to grow, doesn't that mean he would have to grow the tree for like 50 years?