Windows keeps a lot of processes open, each with multiple threads. Most are inactive but can wake up at any moment when the OS sees low enough CPU utilization and thinks something needs indexed, to phone home a metrics report or to check for updates. It goes on and on, and that's why multiple cores on CPU's makes good sense.
It's probably fine. How many threads are "okay to have" does not have a clear answer because it depends on what programs you have running whether you need them or not. This isn't really anything to worry about since almost all of them aren't doing anything. They're waiting on something before they do stuff.