Astrological or "Zodiac" signs are12 symbols, what represent personality values. In the comic, these signs are shown with all characters. The first revelaed zodiac sign was the one of Starscream - Aries.
Every single sign is connected to one of basic nature elements and they too represent one of four looks on the world.
Signs: Aries, Leo, Sigitarius
Signs: Taurus, Virgo, Capricorn
Signs: Gemini, Libra, Aquarius
Signs: Pisces, Cancer, Scorpio