"Born again" is a phrase Jesus used to explain to Nicodemus how a person enters the kingdom of God (John 3:3–7). Jesus said that to enter the kingdom of God, a person must be born again. This means they need a new kind of life from God. It is not a physical birth. It is a spiritual change that comes from God’s Spirit.
Born Again
From Tyndale Bible Dictionary, adapted by Mission Mutual. CC BY-SA 4.0.