It means a condition where one's head is cool and the feet are warm.
Warm feet indicate that blood circulation reached the extremity of the whole body.
On the other hand, cool head means our brain is in a cool, stable, and alert state. Most people are just the opposite. Especially for women. The reasons are that besides their clothing, women have complicated organs such as ovaries and uterus, and the hormone imbalance due to these organs resulted in this problem. Too high or too low a temperature is not good for the body.