It's a pretty sloppy explanation I know xD.
For each skill, those numbers are how much influence the Stat has on that skill, in terms of skill point gain. So for example for the Strength, you have what you quoted:
SG (1/6), BG (3/6), EW (1/6), Unarmed (3/6), Melee (1/6), Throwing (2/6)
It just means each point in Strength will give you +1% Small Guns skill, +3% Big Guns skill, etc. That it says (1/6) and not 1 is just because there are a total of 6 skill points handed out from some stats. The formula for big guns skill (starting value) for example is given by:
BG = 30 + 3*S + 2*A + 1*L
Dunno how to explain it any more pedagogical, but as an example, if you had say 10 in all stats, you would have exactly 30+10*6 = 90 in all skills to start with. With 5 in all stats, as you can see on character creation, you have 30+5*6 = 60. But each stat influences different skills, as suggested by the wiki.
Here's the complete table for those who are really curious