people that are self-conscious are more aware of their looks. 
I don't know a lot about that can you explain?
It is more of a preoccupation with oneself, as opposed to philosophical self-awareness
Like being self absorbed or just fixated on oneself?
No it is associated with being shy and embarrassed. They fee like they are not good enough.
Oh so like a insecure complex?
Yes and it results in lack of pride and low self-esteem.
Is it a mental illness?
No, but some people are just more self-conscious than others.
Ok so its just a personality issue?