The five elements are the basic building blocks of everything. All existing things contian one or more of these basic energies. The elements are called upon in ritual, can be seen in the tarot, the zodiac, and can be represented by the 5-pointed star (each of the five points is a different element).
Air is intellect, the mind and all mental processes and abilities. It is psychic ablities, learning, knowledge and theory. Air is the swords (or knives, or, depending on the deck, wands) in the tarot.
Fire is creative energies. It is a purifier, associated with flame, the sun, blood, healing and destroying. Fire is represented by the wands (staffs, or sometimes swords) by the tarot.
Water is emotion, love, intuition, creativity, and fertility. It's symbol in the tarot is the cup (dish, or culdron).
Earth is the body, growth, nature and all thing material. In the tarot it is the pentacle (coin or disk).
Spirit is the center and circumference, throuhout and about. It's change and transformation. Spirit can be found in the Magician card of the tarot. It is a combination and balance of all elements, and is none of them.