Every GUI objects can be identified by thier property. At least three of this properties are needed to identify them uniquely in a test. Using all this will make the test script look bulky and untidy. So this are saved in GUI map and a corresponding logical name is defined for them. The name like "Edit" that you see in scripts like edit_set("Edit", "ABCD") is the logical name.
Hope that explains your query
If you look at the help files which come with the tool the first few lessons are all about GUI Maps. The point I am trying to make: If you are serious about the tool learning as much as possible about GUI Maps is critical.