What does the angle obtained from the aspect mean?

Discussion created by Jamal432@gmail.com on Nov 18, 2010
Latest reply on Nov 18, 2010 by Dan_Patterson
Please, see the attached image that shows my question

For example, the range of angles between 0 and 22.5 are indicated to be north facing!
What does the angle 22.5 mean?
What does it represent in the reality?
How do we measure it?
Between which two sides does it exist?