The Messages page is a text version of the traffic light. It shows all the alerts that have been raised, their level (severity), and the message. Also, when an Amber, Red or Alarm alert is raised you will see an acknowledgement button appear, as in this image.
You’ll notice that the traffic light mirrors the Messages page, both showing one Amber alert. Ack’ing the alert will then show the alert as being ack’ed and the time it was ack’ed, and the traffic light will change accordingly. Also, any other status indicators, usually LED’s on modules, will also change (usually to green for one minute) to indicate that an alert has been ack’ed. Here’s how the page looks after hitting the ack button.