In lamens terms
The Phase thing just allows you to simulate your subwoofer being "in" or "out" of phase. It has to do with the polarity of the subwoofer. You can simulate the results as if you switched the wires on the back of the receiver (or whatever your sub is plugged in to). Adjust it to where it sounds the best. You probably won't be able to tell much of a difference though.
The frequency: The smaller the Frequency, the more punchy the bass will be. It's a smaller bandwitch of hertz (hz), so it will only produce a limited amount of bass at certain points of the song/movie. If you crank it up to the maximum, 150 hz, the bass will be more broad and the bass will occur more during the song/movie. Because of the bigger bandwith. You won't be able to tell too much of a difference here, either. Glad I could help.