Polarizers only really do anything on an arc described by the intersecting line rotating around the vector characterized by the line from the sun to the camera.... or:
point at the sun (don't look into it, that's bad for your retinas). Now extend your thumb at a 90 degree angle to your index finger. Turn wrist with index finger still pointing at the sun. If the camera points from where it is to anywhere in the sky pointed at by your thumb, you'll get full effect of the polarizer on the sky.
Basically the polarizer rejects scattered light (light that's bee reflected a bunch and no longer retains its cohesive directionality - like being directly from the light source to the subject). It will therefore also help get rid of reflections.
Now, if you're looking for something to dim the window in a house because it's blowing out before your talent, you only have 2 options. Make the subject brighter or make the window dimmer. You can get large sheets of ND gel to cover windows or just use a semi see through fabric like I do and blur the background slightly using various DoF tricks.