This is a standard representation of the warrior god Mars, in a confident though rather flamboyant style. He probably once held a sword and shield, which would have helped to balance the helmet with its lavish crest.
The object is a votive gift, no doubt to a temple of Mars. This is clearly indicated by an inscription on the bronze pedestal. This gives the names both of those who commissioned the object and the man who made it, all of whom were co-dedicators. The text can be translated as:
'To the god Mars and the numen of the Emperors, the Colasuni, Bruccius and Caratius, presented this at their own expense at a cost of 100 sestertii; Celatus the bronzesmith fashioned it and gave a pound of bronze made at the cost of 3 denarii'. Therefore the total cost was 112 sestertii (or 28 denarii) which equates roughly to one month pay for a legionary soldier at that time.