The Sun is a ball of fire, and Mars and Ketu too are Agnikaaraka. If the Sun is connected to Mars, then the native may be connected with activities like making of guns, explosives, etc., since Mars is Bhoomikaraka, and the ingredients used to make dynamite comes from the Bhoomi (Land). If the Sun, Ketu and Mars are all connected then the native may be in a profession associated with electricity, power supplies etc.
The Sun is known as the "Jagat Pita" in the Vedas. So when the Sun has associations with the 10th Lord or the 10th House, the native may work with his father, or else take over and handle his father's business.
If the Sun is related to Saturn and Rahu, then the native can become a Vaid (Chikitsak - Ayurvedic Doctor). If the Sun is related to the Moon, then the native may produce particular types of Sharbat related to its herbs and fruits.
The Sun is a Sattvic planet, therefore its association with the 9th House and Jupiter, can make the native a Purohit in some religious sanstha, or a Pujari, or a Dharmacharya, or a Mathadheesh.
One Guna of the Sun is to "make dry". Hence, a native with associations to Mercury and the 4th House, can make the native deal in dry jadi booti, wood, and dry mewa (kaju, pista, akhrot, kishmish and such dry fruits which are energy producing and good for health (Signification of the Sun).
(The above is written by Bhaskar Jyotish)