Commonly known as a "script kiddie", the work 'h4x0r' implies 'hacker'. People lame enough to use this word are generally not serious hackers, and are most likely using ready-made and easily-found tools on the internet. They generally have little knowledge of the tools that they use or how they work.
The more serious of this group will spend hours and hours a day scanning the internet for computers that are vulnerable to a security hole. They will then exploit that hole (using some pre-made tool) and use what is known as a 'rootkit' to give them 'root' (or total control) over a computer.