en_tn/num/25/04.md

all the leaders of the people

It is implied that this refers to the leaders who were guilty of idolatry. The full meaning of this statement can be made clear. Alternate translation: "all the leaders of the people who are guilty of idolatry" (See: rc://en/ta/man/translate/figs-explicit)

to expose them in the daylight

This means that the leaders of Israel will kill these people and leave their dead bodies out where all the people can see them.