Intuition is just about the same as your sixth sense where a person seems to have that hunch or strong perception when something's about to happen, usually some events that are not good or harmful. A person who has a strong intuition is also called to have a third eye, a mysterious term that has fascinated many spiritual people.
Experts like Maria Duval have said intuition is closely linked to your subconscious mind which can be very active when certain situations and conditions, and that's why it is so difficult to explain this phenomenon rationally.
The reason why Maria Duval and other top psychics is more intuitive is because they have tuned their mind and subconscience to the level that their inner voice or intuition is very sensitive to the difference in psychic energy change. They have learnt to tap their unconscious mind in a more creative way. Or, it may be explained that they have learnt to keep their active mind relaxed and still to enable it to listen to the intuition emanating from the unconscious mind.