Here "sons" stands for those who descended from Heth. AT: "the descendants of Heth" or "the Hittites" (See: [[rc://en/ta/man/translate/translate-names]])
The nominal adjective "dead" can be stated as an adjective or a verb. AT: "my dead wife" or "my wife who has died" (See: [[rc://en/ta/man/translate/figs-nominaladj]])