Extend and as the body goes unwinds to left.
The back of the hand extends down the line as the swing expands its energy from center through ball. The shoulders unwind to the left as the left arm stays connected against the under arm.
The left side braces as the torso moves around the navel center leading the opening of shoulders.
If torso stops its rotation around center the left hand stops it extension through the ball the clubs energy will continue to travel forward either closing the face causing a hook or scooping the ball causing a lofted shot.