What does Genesis 25:14 mean?

The twelve sons of Ishmael, named in order of birth, are given in Genesis 25:13–15. God had promised Ishmael's mother, Hagar, that Ishmael would father "twelve princes." The prediction suggested that each would become the head of his own clan or tribe (Genesis 17:20). As expected, people groups carrying the names of Ishmael's descendants would become influential; in the Middle East and in Israel's history.

This verse continues the list with Mishma, Dumah, and Massa. The descendants of Dumah are apparently referenced in an oracle in Isaiah 21:11–12.