"Renal" means "kidney." A vein is a blood vessel that carries blood toward the heart. So the renal vein carries blood "cleaned" by the kidney, back to the heart.

drains blood from the kidney

major vein taking blood from the kidney into the postcaval vein

veins that accompany renal arteries; open into the vena cava at the level of the 2nd lumbar vertebra

Major vessel which returns freshly cleaned blood from the kidneys to the circulatory system.

Blood vessel that carries blood away from the kidneys.

Short, thick vein which returns blood from the kidneys to the vena cava.

takes blood away from kidneys Humans as organisms

The renal veins are veins that drain the kidney. They connect the kidney to the inferior vena cava.