The ram was one of the most popular sacrificial animals in the Roman world, and were also sacrificed as part of the suovetaurilia; one of the most sacred rites in Roman pagan antiquity. Additionally, rams were often associated with fertility and new life, so it is therefore possible that this bronze figurine could have been a votive offering of some kind.
Bronze was a popular medium for artwork and ornaments in the classical world, as it could be easily sculpted into intricate details due to its ductile nature and low melting point. It was used for a vast range of different items, from life sized human sculptures to small votive offerings, amulets, and figurines.
For more information about the meanings of animals in Roman art, see our relevant blog post: Animal Symbolism in Roman Art.