It's testing moves against each others with varying start up timing, ie, if Chun MK attack start 2 frames before Ryu's HP, which one would win. That's the general idea but we'd have to know what's the rest of the info refers to.
M1 = first move/attack (blue color)
M2 = second move/attack (red color)
Those are the moves tested against each other
X1 and X2 looks like the distance between the 2 characters. Tests covers a distance from .5 to 1.15 for each pair of attacks.
The numbers between M1 and M2 in the header are how many frames the move started before the other:
+7(blue) = M1 started 7 frames before M2
0 = both started at the same time
+5(red) = M2 started 5 frames before M1
The colored boxes between M1 and M2 are the results:
1(blue) = M1 wins
2(red) = M2 wins
3(yellow) = trade(notice this only happens with moves of the same level)
0 = I assume this means whiffed or not tested
Title says Ryu vs Chun li, so M1s are probably Ryu's while M2s are Chun's attacks.