They are called Venus holes, these are small circles, which are formed on the lower back in men and women. In case of men, then these holes are called Apollo holes.
They are located in a place where two bones connect the pelvis, and can be seen only in people who have this genetic predisposition or appropriate size ligaments. We cannot choose whether we have them or not, because it is simple the genetics.
They are a sign of good circulation and a healthy body, and great circulation is an important prerequisite for easier to achieve orgasm.
Since Venus holes are located in a place where no muscle, it is impossible to create them with some exercises, but if you work for the elimination of excess fat, these holes can become visible.