There are already like 4 pages in this thread where we talk about what the numbers signify. You can read those.
or if you'd rather not: the smash community, in general, doesn't assign ratios in non-relativistic ways a la the FGC. We look at the matchups we consider 5-5, and then build our lists out from there, based on which matchups we perceive are "better" or "worse" than others similarly ranked. So if we think Marth-Fox is 5-5, and that Marth-Samus is 6-4, we'd peg a matchup as 55-45 if it is between those two in difficulty for Marth...like, lets say Marth-Peach for instance. If we consider another matchup to be INBETWEEN Marth-Peach and Marth-Samus in difficulty, we'll just bump Marth-Samus to 65-35 and make that matchup the new 6-4. This is very different than the FGC, which assigns numbers less comparitively; they won't call a matchup 7-3 if its not THAT bad, even if its worse than a matchup they pegged 6-4...they'll just call it 6-4 as well to reflect that its "close but in one character's favor." The smash community's methodology is great at being detailed (it is more specific in determining which matchups are harder than others) while the FGC's methodology is better at truly giving a gauge on how easy/hard a matchup is without knowledge of where the rest of the matchups stack up. The end result is that smash numbers tend to be spread out, while FGC numbers are more condensed. So a 7-3 matchup in Melee would often be called a 6-4 in Street Fighter.