en_tn/zec/02/03.md

another angel went out to meet him

This angel is a new person and has not appeared before, and so should be clearly introduced as a new participant. AT: "a new angel went out to meet him:"

The second angel said to him, "Run and speak to that young man

"The second angel said to the angel who had spoken with Zechariah, "Go quickly and tell the man with the measuring line""

Jerusalem will sit in the open country

This phrase means that Jerusalem will not be surrounded by walls.

become for her a wall of fire around her

Yahweh is saying he will protect Jerusalem and compares his protection to a wall of fire. (See: rc://en/ta/man/translate/figs-metaphor)

this is Yahweh's declaration

This phrase is often translated as "Yahweh says" in the UDB. You can translate this concept whichever way is best in your language. This phrase is used many times in Zechariah.