Cernunnos is generally thought to be a God of fertility. Thus, he was called upon to bless weddings and to ensure plentiful harvests. He is typically depicted with other animals because he was thought to be a shape shifter and often appearing in the form of a snake or a stag.
People wear jewelry with his image these days as a link to those days or because they find the image pleasing. Although Cernunnos is generally viewed as a universal God revered by all Celts these days, some scholars believe that Cernunnos was a relatively local deity of consequence in a limited area (see Balmires book “Glamoury” for more detail on this point).
