Fractional style shows as one number over another number. For example, you might see bet365 odds at 10/1. That means that for everyR$1 you bet, you'll receive an additionalR$10 for a winning bet. PGA odds are displayed in this format by default. Lastly, you have decimal format.

It goes like this: Place a 2nd place cover bet on a horse. This means if it wins you get the payout at the odds offered, however if it comes second, your stake is refunded. If it comes third or more you lose the stake.