It's a constant combinator that automatically outputs signals related to the incoming CME on the surface where the combinator is placed. This is the same info you can see in Informatron.
This can let you react to CMEs in a more automated way. Lights, alerts, switches, battery toggles...

The number displays in the screenshots are from Nixie Tubes.

Details

The combinator only outputs signals when the surface it is placed on is planned to have a CME. No signals are output otherwise.

• S signal: Number of seconds until the CME hits. When it hits 0, the CME will start. The number of seconds will go into negatives while the CME is ongoing. After the CME has passed, the combinator will reset.
• W signal: Peak wattage in MW.
• J signal: Total energy required in MJ.

Will this eat my UPS?

Circuit entities added by mods are never as performant as vanilla entities but this mod does its best to save on UPS:

• Combinators only update values every second. If you place combinators on several surfaces, each surface will be processed on a different tick to spread the load.
• The mod only refreshes the CME information from Space Exploration every minute.

Given that you won't place more than a hundred of these combinators, I don't expect it to have any impact on your UPS.