During the story, you’ll eventually acquire the ability to Lift and Slam enemies using the Force. To Lift, hold RB and Y. Initially, you can only do this to smaller foes, but if you pour Skill Points into this ability, you can Lift larger enemies. Simply Lift an enemy and attack them, performing this 20 times to unlock the achievement. You might have to jump a bit to reach them while they’re suspended in mid-air, or you can use Cal’s blaster.