Settings & keep-time · Services and self-healing
What does the Free Up Space engine row in Settings → Services show?
Short answer: It shows the Free Up Space engine's state: Running now, Idle with roughly how much the last run freed, or Ready to run until you press the button or the daily schedule starts it.
It reports the engine behind the Free Up Space button and the scheduled run. Running now means it's cleaning caches and moving large items; Idle shows roughly how much the last run freed on your internal disk; Ready to run means it's waiting for you or for the daily schedule.
It's normally green. If space isn't coming back as expected, see freeing space.