en_tn_lite_do_not_use/neh/08/01.md

All the people gathered as one man

The word "all" is a generalization that indicates the people as a whole came together. AT: "The people gathered all together" (See: rc://en/ta/man/translate/figs-hyperbole)

Water Gate

This was the name of a large opening or doorway in the wall.

the book of the law of Moses

This would have been all or part of the first five books of the Old Testament.