The indicator appears as a colored bar along the top border of the Cue tile. It provides a visual signal of the status of the Cue's activity, which can indicate favorable or unfavorable conditions to prompt the user to take action. For example, if a Cue displays ongoing sales invoices, you can set up the indicator to appear green (favorable) when total number of ongoing sales invoices is below 10, and appears red (unfavorable) when the total is greater than 20.
From the "Activities" drop down, select Set Up Cues:
For additional details check out: