Super-Ignorant Question

Can someone explain the difference, or expound on exactly what, getproperty and setproperty do? Are there other things that you can get and set? In some cases, it seems that with AS you can just make stuff up, I’m learning the difference between simply coding (using a preset group of scripts) and using AS as a Language (making stuff up and making it work). I found a script recently that had a setup like this:

q=0; //q is zero
while (q<=3){ //while q is less than 3, which is always(?)
mky = getProperty(“this.clip.mk”+q, _y)+10
mkx = getProperty(“this.clip.mk”+q, _x);

           // I suck at math! This is why I became an artist! This means that

mky is the property from “this.clip.mk”+q //isn’t that meaningless, since q is zero?// times a y value, with the sum plus 10? Am I even close to right? Perhaps they’d pay to send me back to remedial algebra… I want to be able to understand AS fluently, and I think I’m on my way. I know this is a lot to discuss, this question isn’t seeking an answer to a definitive problem so forgive me for being nebulous. Thanks to anyone who helps me learn. -Dan