This Enoch was the son of Cain for whom Cain named the city he built.
Biography
Genesis 4 says Cain knew his wife, who bore Enoch. Cain then built a city and named it after his son Enoch. The genealogy continues through Enoch's son Irad and eventually to Lamech and his children. Scripture provides no other narrative about Cain's son Enoch.
Biblical Significance
This Enoch belongs to Cain's line and must be distinguished from Enoch son of Jared in Seth's line, who famously walked with God and was taken by God.