There are two types polarizing filters, linear and circular. The circular version is the most common as it doesn’t interfere with autofocusing on digital cameras. The linear type is if you don’t mind manually focusing and exposing your images. The circular version turns to select different levels of reflected light.

The linear and circular are both exactly the same except the circular has an added ‘quarter wave’ plate. The focusing issue has to do with polarized light not reflecting off a mirror. DSLRs have a mirror that splits the incoming light between viewfinder and focusing units.

If your camera has no internal mirror, linear is fine; it wont affect your auto-focus.

Both versions (w quarter plate and without) rotate but not exactly to ‘select different levels of reflected light’, but to change the plane of polarized light coming into the lens. Non reflected light is in pretty much all planes. Reflected light is polarized in a plane relative to the reflecting surface. The end result is much the same, but if you were wondering why your polarizer reduced some reflections but not others at the same time…

BTW/FWIW, back when I was shooting film, I had all sorts of filters. These days I carry a cPol and a couple of NDs (for short DoF in bright light) — and that’s it. Everything else can be done in post, although if I would have otherwise used a grad, I stack exposures (most DSLRs can do a stack fast enough that handheld is fine).