An "oven timer" is a device in an oven that helps you keep track of how long your food has been cooking. It beeps or makes a noise when the set amount of time is up. Full definition
For example, users can say «Ok Google, ask Geneva Home to set the oven timer for 10 minutes,» which will tell the GE connected oven to set its timer. (fortune.com)
(anyone else have a husband that always sprints into the kitchen to sample stuff as soon as the oven timer goes off?!?) (deliciousbydre.com)
I set my oven timer to 50 minutes and unfortunately that was too long and it burnt the top of the cake. (ambitiouskitchen.com)