If you pick the option Breakfast, Lunch, or Dinner, it will give you the time that it finds the most availability.. i.e. Dinner at 8:30 pm.
If you don't care about the time, then go by the word. If you want a specific time, pick that time and you'll get the closest to your chosen time.
If you have an odd number in your party and can't find a reservation, up the party by 1 to even it out and try again.