Leo's are the energy of the 5th house in the natal chart and each zodiac sign rules a house. Aries starts the order with it's traits in the first. As the signs travel in order like Aries, Taurus, Gemini, Cancer then Leo would be the the 5th house.
The houses are the enviornment where the planets travel through depending on the day and year. If a Leo women is born in the early morning (4am-6am give or take a few minutes) she would be very dominant expressing the Leo traits. Or if a person born no matter what their sign but has Leo rising they would seem like a Leo. In the astrology books the traits of Leo's are threatrical, outgoing nature because it is one of the fire signs, The 5th is the house of children and speculation, gambling, and love affairs. Key words associated with the Leo are Loyal, proud, generous, and expressive .Leo's ruling planet is the vibrant Sun and they are known as Leo the Lion.
When you put all these elements and connect the words it shows a very strong and normally outgoing sign with a lot of energy and strong sense of being. They are often the hit of the party. Several actors are Leo's which fits with the threatical side. I know two Leo women whose personality are very similiar. One sales ads to TV and radio stations and the other is a partner in a real estate company. Both these women are very outgoing and very likeable and come across very self confident.