I have a little experience with polarizers—and I think they are loads of fun to work with.
Yeah, that looks like it’s a decent filter. (Okay, perspective-wise, I have an AmazonBasics CPL filter… ten bucks and cheap, but it’s fun to play with and I can still get polarized results.) I think I was looking into Hoya for a different filter set (ND, I think—I ended up going with something else), but I can’t remember how great it is or isn’t.
A polarizer is basically reduces all light coming from a specific direction. Light bounces all over the place—a polarizer helps to isolate only the light you want.
So if I’m shooting a sky, light is bouncing all over it from the sun, and light is bouncing off of the sky at me. So when I look at it on a clear, sunshiney day, it’s a light blue. If I used a CPL filter, I could block a lot of the light coming off of the sky—and I get a darker, deep blue sky. This is really useful when you are shooting a partly cloudy sky. A CPL filter darkens the sky, and leaves the clouds lit up. So I have a very dramatic and high contrast sky.
A CPL filter also cuts reflections, as @rmadaris was saying. I can turn the filter so it reduces the light coming off of the water. By doing so, I can see past the reflections and glare straight into the water. (This is why people who like to fish wear polarized sunglasses—it helps cut the glare on the water so they can actually and physically see the fish under the surface).
Bryan Carnathan over at the-digital-picture.com has a good article about CPLs: https://www.the-digital-picture.com/Reviews/Circular-Polarizer-Filters.aspx
Hope this helps, and have fun!