If your Beacon appears as dormant (previously inactive) it means that no device has received notifications from that beacon in the last 7 days.
It can either mean one of the following things-
No mobile device came in the range of that beacon (with location and Bluetooth turned on)
The battery of the beacon has been exhausted.
The beacon is turned off.
To make sure that the battery is fine and the beacon is turned on you can go through this article.
If you find that the battery is exhausted or your beacon is turned off you can check this article to troubleshoot further.