Numbers 10:4

Modern

But if only one is sounded, then the leaders, the heads of the clans of Israel, are to gather before you.

Traditional

And if they blow but with one trumpet, then the princes, which are heads of the thousands of Israel, shall gather themselves unto thee.

Literal

But if they blow with one, the leaders, the heads of the divisions of Israel, shall gather to you.

Latin

Si semel clangueris, venient ad te principes, et capita multitudinis Israël.

Hebrew

English

But if only one is sounded, then the leaders, the heads of the clans of Israel, are to gather before you.

They used the two trumpets to alert people for important announcements (compare Revelation 8–11).

Israel needed clear signals so the tribes could receive instructions. Two silver trumpets provided a simple and effective way to signal all the tribes to move.
These trumpets were not the ram’s horns (Hebrew shofar) often mentioned in the Old Testament (for example, Joshua 6:4–6). Israelite craftsmen made them from hammered silver brought out of Egypt.

Numbers 7:2
And the leaders of Israel, the heads of their families, presented an offering. These men were the tribal leaders who had supervised the registration.
Exodus 18:21
Furthermore, select capable men from among the people—God-fearing, trustworthy men who are averse to dishonest gain. Appoint them over the people as leaders of thousands, of hundreds, of fifties, and of tens.
Numbers 1:4–16
And one man from each tribe, the head of each family, must be there with you.
Deuteronomy 1:15
So I took the leaders of your tribes, wise and respected men, and appointed them as leaders over you—as commanders of thousands, of hundreds, of fifties, and of tens, and as officers for your tribes.

Israel: Patriarch, son of Isaac, father of twelve tribes