In very simple noobie terms, rooting your phone means that you use a 'root' application that allows you to be able to access your system settings to do things, remove stock apps, etc., that you cannot do unless your phone is 'rooted'.
In almost every different phone forum you will find threads that are dedicated to rooting your specific phone.
Whatever you do be careful when you perform this operation. It is very simple when done correctly but you can mess up your phone if you aren't careful.
Good luck!