A great exercise that targets your arms, back and core!!
Although you may see the plank row perform from the floor, I like performing this exercise at an incline because You get more range of motion using you arms, thus making your core do some work!
Form to make sure you are getting quality effectiveness:
Stabilizing arm kept directly under shoulder for foundation
Hope/butt tucked in, while in plank position
Inhale when pulling, exhale when lowering the weight
Keep hips square with the floor. Do not shift or rotate while pulling with the arm