Circles represent wholeness and protection. Circles represent life. In total there are 7 circles. I am heavily influenced by my studies of Taoism and Qigong. As so I look to the Chinese interpretation of the number 7.
The Chinese meaning for the number 7 is as follows:
Seven is the number of a perfectly completed cycle, as each phase of the moon lasts for seven days (the four phases of the moon form a complete cycle). This may be why so many ceremonies and festivals in China are celebrated on the seventh day - to seal the perfection of the occasion and to commemorate the intention of the event. The theme of time cycles is repeated when we see Chinese philosophy deems the number seven as a symbol of woman-ness (also connected with feminine moon cycles). The idea of perfect timing and the ordering of nature is expressed with the numeric union of the 4 (symbolic of Earth in Chinese philosophy) and 3 ( symbolic of heavenly attribute). Number seven tells us that to everything there is a larger, grander, more divine construct that sustains life. Perhaps that construct is comprised of the energies of the seven Chinese gods of prosperity: Ebisu the god of business, Daikoku the god of wealth, Bishamonten the god of war, Benzaiten the goddess of the arts, Hotei the god of health, Jurojin god of wisdom, and Fukurokuju god of happiness. The Chinese zodiac symbol for seven is the Horse, and South is this number's Feng Shui coordinate.