Holy baptism is a ritual of Christianity-baptism. When the Israelites reach the age of 30, they will be baptized in the Jordan River. Nowadays, most Christians take a little water ceremony (the priest sprinkles water on the head of the baptized person), and some more devout churches continue the big water ceremony (that is, the whole body is immersed in water, preferably running water).
Being baptized symbolizes that the old me is dead, and God has created a new holy me, which means that being baptized means dying with Jesus and being resurrected.