Catalyzes the dephosphorylation of histidinol-phosphate to histidinol, the direct precursor of histidine. H2O + L-histidinol phosphate = L-histidinol + phosphate Binds 1 Mg(2+) ion per subunit. Amino-acid biosynthesis; L-histidine biosynthesis; L-histidine from 5-phospho-alpha-D-ribose 1-diphosphate: step 8/9. Inactivation of the gene results in growth defects and incomplete auxotrophy of the mutant due to a deficiency in histidine synthesis. The growth defect of the mutant is rescued by expressing hisN from C.glutamicum. Belongs to the HAD-like hydrolase superfamily. SerB family.