Mike, the slope refers to how "severe" the crossover's cutoff is, measured in decibels per octave. A 6dB/octave crossover reduces a signal more gradually than a 12dB/octave crossover -- which is twice as steep. This page has a graph that should make it clear:

http://www.bcae1.com/xovrslop.htm


I can explain it to you but I can't understand it for you.