The Sun stands for principle of selfhood. It means vitality, personal power, leadership and dignity. The Sun represents eternal renewal, and the shining virtues of both truth and light.
Mandala is healing medium for the soul; the emerging of body, spirit and soul. You become calm, gain trust and composure.
Mandala usually is projected as circular designs (sometimes within a square or rectangle) that creates a focus for the mind. It is a tool for meditation in Tibetan Mandalas and as a creative pursuit that brings healing.