It is an acid salt because ammonium ion hydrolyses slightly in water. Basically Ammonium Bromide is a strong electrolyte when it reacts with water. Ammonium bromide decomposes to ammonia and hydrogen bromide when it is heated at a high temperature.
Ammonium bromide is used to manufacture chemical intermediates, and in photographic chemicals. There are two fluoride salts of ammonia: ammonium fluoride, principally a laboratory reagent, and ammonium bifluoride, used primarily as a less hazardous substitute for hydrofluoric acid.