Not all ovens have that. Pretty sure mine doesn't, though my induction hot plate does. And tbh it's kinda annoying because the timer finishing doesn't always mean it's done cooking, it might just mean time to add the next batch of ingredients or flip whatever is baking. But I've got two other timers on other devices within reach, so I just pick the most convenient one for the current objective (or just look at the time and try to remember on my own).