Quick Lesson...

There are 4 elements in Western Astrology.

FIRE, EARTH, AIR, WATER.

FIRE:
Aries
Leo
Sagittarius

EARTH:
Taurus
Virgo
Capricorn

AIR:
Gemini
Libra
Aquarius

WATER:
Cancer
Scorpio
Pisces

The Fire and Air elements are both MASCULINE zodiac signs, Earth and Water FEMININE.
Masculine simply means more active, less receptive. Feminine signs are more receptive, sensitive, and emotional.
Masculine signs are more compatible with other Masculine signs, and Feminine with Feminine signs. 
*Remember, Fire and Air rise, Earth and Water are subject to gravity.