Not trying to be lame, but each mod clearly spells out what they do in terms of whole number increases to stats or percentage addition to stats. If you're asking about what the icons mean, then look at the mod challenges in the game and that will tell you what each icon means.
You can also do a search here for "mod guide" and I'm sure a couple of threads will pop up. GL.
Replies
You can also do a search here for "mod guide" and I'm sure a couple of threads will pop up. GL.