By definition, debugging is a methodical process of finding and reducing the number of bugs in an application. Normally, the first step in debugging is to attempt to reproduce the problem. On some occasions, the input of the program may need to be simplified to make it easier to debug. Then, the debugger tool is used to examine the program stats (values of variables, call stacks, and so on) to track down the origin of the problem(s), and, finally, fix it.
Debugging, however, can do so much more than just solving issues. It is a fantastic way to understand how an application works. You could just open the involved object, read the written code, and follow it up. However, it will be hard.
First of all, Dynamics NAV code is run after an event occurs. If you take a look at an object, you will see code in the events, but it will be hard to know when an event occurs or which event is the one that first causes the code to be executed.
It will also be hard to just read the code...