The numbers 36-24-36, also known as the "hourglass" figure, are measurements (in inches) for the bust, waist, and hips respectively. This ratio has traditionally been considered the "ideal" body proportion for women, as popularized by fashion, media, and beauty industries.
However, it's important to understand that these measurements are not a standard of health or fitness. They represent an aesthetic ideal that varies across different cultures and historical periods. In reality, healthy and fit individuals can have a wide range of body proportions. Furthermore, focusing too much on achieving specific body measurements may lead to unhealthy behaviors and body dissatisfaction.