For example,
If your left hand was doing the lifting:
The right hand would be grabbing the top right of the bench, the right knee would be on the bottom right corner of the bench, your left leg would be to the straight, to the side, and you would grab the dumbbell and lift it up with your left hand.
What is this exercise called and what does it work?

i am 14, boy, 125 pounds. i have access to 5,20,30,40 pound dumbbells. i currently do 20 reps of 20 twice a day. is that good? for a standard dumbbell bicep curl?

i have a 15 and 25 lb dumbbell. i don't know which one to use to gain muscle mass. i can do a max of 40 reps per set for 15 lb and 3 reps per set for a 25 dumbbell. i can't buy a 20 lb. one for now.

I weigh 10 stones and i am 5ft 9inches, how much should i be lifting with my right arm, with 1 dumbbell

For example,
If your left hand was doing the lifting:
The right hand would be grabbing the top right of the bench, the right knee would be on the bottom right corner of the bench, your left leg would be to the straight, to the side, and you would grab the dumbbell and lift it up with your left hand.
What is this exercise called and what does it work?

For example,
If your left hand was doing the lifting:
The right hand would be grabbing the top right of the bench, the right knee would be on the bottom right corner of the bench, your left leg would be to the straight, to the side, and you would grab the dumbbell and lift it up with your left hand.
What is this exercise called and what does it work?