If you place a bet on the number 0 in roulette and the ball lands on that number, you win. In most casinos, the payout for a winning bet on 0 is 35 to 1, meaning you receive 35 times your original bet. This can result in a significant win if you've placed a substantial bet on 0.
The probability of the ball landing on the number "Zero" in a standard European roulette wheel is 1/37, or approximately 2.7% of the time. This is because there are 37 numbers on the wheel, including the single "Zero" pocket.