I'm playing lacrosse for the first time this spring, and just bought a stick. But I was wondering I've heard about people burning (?? ) off the excess string or something like that to fit the pocket for their individual preference. But what exactly am I supposed to do with the excess string leather stuff?

I have seen people do that and all my sticks are like that. What you have to do is cut off the excess string and light a match and burn off the tip so its doesn't fall apart. It doesn't make the pocket bigger or smaller it just take off the ends of string so you won't get hit with it or annoyed.