What is the signifier?

 It's a bronze bull in the middle of a city. More specifically in New York City. The statue appears quite large and the bull seems to look like an angry Spanish toro than a peaceful Hindu Calf.

What does it signify?

Knowing that this bull is is near Wallstreet and knowing that the term "Bull Market" is when the economy is on the rise. Seeing the aggressive nature of this bull it seems to infer that not only will the economy rise but it will do so aggressively.. Or maybe it means that one has to be aggressive to see their portfolio rise. This would make sense to anyone who has seen the stock floor.

What supports my analysis?

I feel the location and position of the bull most likely support my analysis. If the bull was in any other place on the planet I'd have no way of being able to tell what it was supposed to signify.