Baptism means (1) to be washed (2) to be buried (to be immersed) and in spiritual meaning, (3) to pass on sin by laying on of hands, as ministered in the Old Testament days.
In the New Testament, the baptism of Jesus by John the Baptist was to wash away all the sins of the world. 'The baptism of Jesus' has the meaning of taking away the sins of all mankind, to wash away the sins of the world.
Jesus was baptized by John the Baptist, the representative of all human beings and the High Priest of the lineage of Aaron, and took all the sins of the world upon Himself. This was the purpose of His baptism.
The spiritual meaning of the word 'baptism' is 'to pass on, to be buried.' So, "the baptism of Jesus" means that all sins were passed onto Jesus and that He was judged instead of us. In order to save mankind, Jesus had to take away our sins with His baptism and die for them.
Thus, His death is also the death of you and me, all the sinners of the world, and His resurrection is the resurrection of all people. His sacrifice is the salvation of sinners, and His baptism is the very witness to washing away all the sins of humankind.

The Bible tells us, "There is also an antitype which now saves us, namely baptism" (1 Peter 3:21). The baptism of Jesus is the righteous way of saving all humanity by washing away our sins.