Everything is fine. There are no current alarms.
There was an alarm that has now ended.
This could mean that device was offline for a while, or that the temperature was out of range for a while.
To clear back to green, click on the Location and scroll down to the alarm section. Then acknowledge and close the alarm.
There is currently something wrong.
This can mean that the temperature is outside the set limits, or that the Gateway or Logger is offline.
You can acknowledge this alarm, which will stop you receiving further alerts, but you cannot close it until the alarm condition has passed.