To understand what the sight of the psychic entails, let's first take a look at how physical sight works.
If you ask someone what do we see with, the answer you are most likely to get is 'eyes'. Though this is not incorrect, it is only a partial answer.
The physical eyes send pure, unprocessed data through the nerves in to the brain. At this step, this data is meaningless, and therefore useless.
The brain's job is to establish relationships, and thus convert meaningless data into meaningful information. This is where actual sight is created.
The competent psychic understands this process thoroughly and confidently steps beyond into the realm of awareness.
What is awareness? Everything is - we live in a sea of awareness.
In this context, awareness is the final step in the process of sight: The physical eyes see, the brain interprets data, and the awareness applies the information into itself.
The psychic's sight, the sixth sense is created by simply paying attention to this process.
We absorb a vast multitude of data through our senses. An even vaster multitude of information is created and absorbed repeatedly in the brain. Our non-conscious awareness handles most of it and passes on the top of the crop to our conscious awareness - that is the 'self' we usually identify with.
As I said, everything is awareness. It is the building block of reality. Even the brain is just a funnel through which awareness can stream.
A master psychic understand that he/she is one with the process of sight, and uses this realization to access any aspect of awareness he or she chooses.
Although the road to mastery may not be so short, understanding the basics is immensely helpful and will get us there much more sooner.