John Gill Commentary Nehemiah 3:19

"And next to him repaired Ezer the son of Jeshua, the ruler of Mizpah, another portion, over against the ascent to the armory at the turning [of the wall]." — Nehemiah 3:19 (ASV)

And next to him repaired Ezer, the son of Jeshua, the ruler
of Mizpah

Either of another Mizpah, or of the other half of Mizpah, (Nehemiah 3:15).

another piece ;

or a second piece; one of the two pieces; for another is mentioned in the next verse:

over against the going up to the armoury, at the turning [of the wall] ;

the western wall towards the south, near to which was a place where armour was laid up; perhaps the same with the tower of David, to which there is an allusion in (Song of Solomon 4:4) .