How do you interpret "12 hrs power" in Activity Monitor?

When hovering over the *12 hrs power* column header in the Energy tab of Activity Monitor, it says: > Average Energy Impact over the last 12 hours or since the Mac started. Lower is better. In my case, WhatsApp is "37.34". Since we're told "lower is better", it can be inferred that it is using a *lot* of energy relative to other applications - but 37.34 *what* exactly? (is it a % of total power use, an absolute measure in some electrical metric, or something else?)