What does it mean to be born again? Well, let's see:
What does it mean to be born? Life begins at conception, when a sperm (one of millions) penetrates the egg and fertilize it. A chain reaction of multiplication and specialization of cells start to take place, and over time, it gives the shape and characteristics of the person to be born. Birth is the culmination of the complete formation of the human being.
What does it mean to be born again? Spiritual life begins when God enables the person (egg) to receive His drawing (sperm). A chain reaction starts to take place where gradually and progressively the person starts to receive the Word of God through reading the Bible, participating in Bible studies, praying and meditation. The culmination of this process is when the person decides to accept Jesus Christ as his/her personal Savior, repents of his/her sins, receives biblical baptism and dedicates the rest of his/her life to Jesus Christ.
Everybody is born in the flesh, but few get to be born of the Spirit.