As different from a multi-race bet, an intra-race bet comprises one or more predictions in a single race.
For instance, a win or place bet, where the player has to identify a single horse; an exacta, where the player must isolate both the race winner and the runner-up; or a trifecta, where the player must go a stage further and also predict the third placed horse.
So an intra-race bet is a bet contained within one race, with one or more predictions within the race.