A yantra is a mystical diagram that is the house in which a Devata (God or Goddess) dwells. Worship of planetary yantras is used to remove the ill effects of malefic planets and to increase the positive influences of favorable planets.
Surya is the God of the Sun and is one of the nine primary celestial beings in Hindu Vedic astrology who are the agents of the Law of Karma. This yantra shows the Sun's symbol, the Zodiac sign that the Sun rules, and the mantras associated with the ruling deity, Ramachandra Deva. The Sun symbolizes cosmic intelligence, pure consciousness or the enlightened mind. The Sun is God, the Divine incarnate in nature.
I pray to the Sun, the day-maker, destroyer of all .sins the enemy of darkness, of great brilliance, the one who shines like the red hibiscus flower. - Navagraha Stotram