The red dots on the Sleep Insights section indicate when the crib successfully soothed your baby to sleep without any caregiver intervention. If your crib is in auto mode, it may kick in multiple times a night, but you'll only see it categorized as a soothe if your baby goes back to sleep.
Please note that only instances when your baby slept for at least 30 minutes due to the soothing are considered "soothes". This additional qualification ensures that only effective "soothe" counts are displayed.