heads: i.e. chiefs or princes of the People. The number not stated here, but must have been 1,000, and included in the 24,000 of Num_25:9, and excluded in 1Co_10:8. The 23,000 mentioned in 1Co_10:8 "fell in one day": the day of the plague, verses: Num_25:9, Num_25:18. And those who were hanged prior to that (verses: Num_25:4, Num_25:5) are not included.
hang them up: i.e. impaled or nailed to a stake, as in crucifixion (Vulg, renders it "crucify", which means the same thing).