OET interlinear NEH 4:18

uW Translation Notes:

Note 1 topic: figures-of-speech / idiom

וְ⁠הַ֨⁠בּוֹנִ֔ים אִ֥ישׁ חַרְבּ֛⁠וֹ אֲסוּרִ֥ים עַל־מָתְנָ֖י⁠ו וּ⁠בוֹנִ֑ים

and,the,builders (a)_man sword_of,his strapped on/upon/above/on_account_of//he/it_went_in hips_of,his and,[they_were]_building

In this context, a man means “each person.” Alternate translation: [each builder worked with his sword strapped to his side]

Note 2 topic: figures-of-speech / explicit

וְ⁠הַ⁠תּוֹקֵ֥עַ בַּ⁠שּׁוֹפָ֖ר אֶצְלִֽ⁠י

and,the_[one,who]_gave_a_blast (Some words not found in UHB: and,the,builders (a)_man sword_of,his strapped on/upon/above/on_account_of//he/it_went_in hips_of,his and,[they_were]_building and,the_[one,who]_gave_a_blast on,horn [was]_beside,me )

The implication is that Nehemiah stationed this person next to him so that he could sound a signal if needed. (This becomes clear in 4:20.) If it would be helpful in your language, you could say that explicitly here. Alternate translation: [And I stationed someone next to me who would blow a ram’s horn if we needed a signal]