As far as I understand it, it is a big system file that apparently controls a big part of the phone. I am interested because I wanted to do some themeing and so far I had edited SystemUI.apk, but if I ever ran into any problems (and being a beginner that was bound to happen) nothing seemed to happen other than the fact that I lost my notification bar.
Problem is, I have heard of some people who touched framework-res.apk and they wound up not being able to even boot their phone. I decided before carelessly poking around with something that could potentially soft brick my phone, I would like to learn a bit more about it.
So what exactly is framework-res.apk? What is it used for? What does it control? Where do we visually see its use? What could potentially happen to my phone should something go amiss with framework-res? Anything else I should know before poking my nose where it shouldn't be?