Baptism symbolizes dying (buried) with Christ and to self and then rising to a new life in HIM in this present life and for life in eternity. It also means that a person has decided to follow Jesus and now there is no turning back to the old way of life. In another sense, it reflects repentance and forgiveness and acceptance by God.
In a symbolic way. the waters of baptism means having your sins washed away and being resurrected to newness of life in Christ. In other words, becoming a New Creation in Christ. ( 2 Corinthians 5:17 ) and receiving the Holy Spirit.