My zodiac sign defines me perfectly. How is that possible and are zodiac signs biblical?

Hey.. Thank you for the question.
You take up the newspaper(like in the olden days) or a website and go through the zodiac signs and wonder - "wow this is so me!"
Well - while there are some of us who have that experience, there are many others who don't see any similarity with the mentioned personality traits.
It's just a pure coincidence and there is not any evidence to support the validity of zodiac signs. And more importantly, astrology (interpreting the stars and their positions to have a divine meaning connected to an individuals personality trait or purpose) is something the Bible condemns. (do read the recommended articles for seeing the Biblical references - really helpful)
As a Christian, we don't study the stars to find our purpose or know more about ourselves - but go to the Creator Himself. He alone can help us discover our true identity and purpose.