According to Engadget, a yellow light flashing in slow bursts on an Amazon Echo means Alexa has a message or notification to share. The notification system, introduced in 2017, can alert users to calendar reminders, package shipments, price drops, and other updates from Alexa features and skills.
To clear the yellow light, users can ask Alexa questions such as "What notifications do I have?" or "What messages do I have?" Alexa will read the list aloud, and users can respond with phrases like "next" or "repeat." For missed reminders, saying "What are my reminders?" lets users dismiss, snooze, or reschedule them.
Notification settings can be customized in the Alexa app by navigating to More > Settings > Notifications. From there, users can toggle alerts for reminders, skills, and connected camera devices. Engadget's guide is the only source provided, so there are no differing reports to compare.