i dont get what dose do Quality?

[xxxlewisxxx11]

i have Quality on all my stuff and it just like 5 Quality what dose it do?

[Granger]

The quality of your stuff modifies the quality of stuff you do with your stuff.

So the better quality your stuff is, the better the stuff you build with it will be (and in case of food the FEP you gain from it).
You need some skills and attributes though, since then either raise the quality of the resulting stuff (or even cap it).

[Potjeh]

More damage for weapons, more FEP for foods, higher bonuses for equipment, etc. Generally, 10 is taken as baseline quality. Quality increases effectiveness according to this formula: sqrt(quality/10) * baseline. So, a q40 sword will do twice the damage of a q10 one, q90 will do 3x, q 160 4x etc.