RobH_en_tn/num/10/06.md

When you blow a loud signal

Here the word "you" is plural. Yahweh is speaking to Moses, but he is referring to the priests. The priests will blow the trumpets, Moses will not. Alternate translation: "When they blow a loud signal" (See: rc://en/ta/man/translate/figs-you and rc://en/ta/man/translate/figs-metonymy)

the second time

"time number 2" or "again" (See: rc://en/ta/man/translate/translate-ordinal)

They must blow a loud signal for their journeys

"They" refers to the priests and the word "their" refers to the people of Israel.