In my experience, a Scheduler is something that schedules time on the CPU for processes (threads).
So 10 processes (threads) say "I need to do something":
2 of those threads are "ready to continue" because they were previously waiting on some Disk IO (and responsibly released thread control while data was fetched).
1 of the threads says "this is critical for GPU operations".
1 of those threads self declares it is elevated priority.
The scheduler decides which of those threads actually gets time on an available CPU core to be processed.
I only know how long bald eagles burn for.
How do I convert microwave hours to bald eagle burn time (in number of football games including all dead ball times and the halftime shows)?