go to the track
Hello I'm watching another episode of the Charmed.
Phoebe, who possesses the power of premonition (it enables her to see into the future) is talking with her sister, Prue, about an Armani dress she is going to buy.
Prue: How are you going to pay? You're broke. You didn't use your powers again?
Prue: What, did you go to the track, play the market, what?
Could tell me what Prue means by "go to the track"? What kind of track?