J =0: both L and S lie head-to-tail with opposite directions. This configuration cancels out their contributions, resulting in a zero total angular momentum (J).
J =1: L and S lie perpendicular, so there is a small cancellation of some of their angular momentum. But there is a total angular momentum J pointing inbetween L and S.
J =2: L and S point in the exact same direction, adding up to the largest total angular momentum possible.