Please go ahead and open up wikipedia, you have a bit of reading to do:
- Revision control
- Subversion
With that reading done, you should have a better understand of what source control is. As a programmer, I'm pretty sure you'll find it makes sense to "save" what you're working on, making changes incrementally and being able to go back to those changes.
In a nutshell, revision control is the ability to go back in time, so that you can read code you have written at that moment.
