There are quite a few web links that explain RF polarization. H & V is quite easy to comprehend. If you imagine tying a rope to a pole and shaking the loose end up and down until it whips in a wave. That's vertical polarization.
Of course if you whip the rope sideways 90 degrees from vertical, that's horizontal polarization.
At low frequencies like Zeta explained. You will notice some signal loss if the transmitting antenna is vertical like an old car radio antenna. And your receiving antenna is horizontal.
The big change comes at microwave frequencies. The receiving antennas in an lnbf for linear polarized reception can be seen oriented 90 degrees in the throat. At these frequencies a great amount of attenuation can be gained between identical satellite transponder frequencies with perpendicular polarization. Your receiver will send a signal to tell the lnbf electronics to switch between the "probes".
Satellites also use circular polarization. Like the coils of a long slinky. Wound either clockwise or ccw.
The antennas on them are constructed to generate the "slinky". And at these frequencies, the receiving end equipment can easily discriminate the polarization.
But. Your dish is a mirror. So when a right hand circular polarized signal is reflected off of the surface. It turns into a left hand polarized signal. The lnbf handles that well because of it's design. H & V polarized signals just get reflected and stay the same.
The 'skew' angle of your dish and lnbf (offset feed) varies according to if you are pointed East or West of true South.
You see the horizon as a flat line across your yard. Parked above the equator, satellites in the sky follow it. And so as you aim at different sats., you need to tilt the dish (skew it) to compensate. On a prime focus dish with the lnbf at the center. The lnbf itself will be tilted. A tracking dish (polar mount) for either c or ku band carries the tilt with their movement across the arc.
There's more. I'm sure the guys will pipe in of the particulars of circular polarization and no real need for accurate skew and stuff.