Has hexosaminidase activity. Responsible for the cleavage of the monosaccharides N-acetylglucosamine (GlcNAc) and N-acetylgalactosamine (GalNAc) from cellular substrates. Has a preference for galactosaminide over glucosaminide substrates. Hydrolysis of terminal non-reducing N-acetyl-D-hexosamine residues in N-acetyl-beta-D-hexosaminides. Inhibited by O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino N-phenylcarbamate (PUGNAc) (By similarity). Inhibited by galacto-NAG-thiazoline (By similarity). Homodimer; disulfide-linked. Belongs to the glycosyl hydrolase 20 family. Extended N-terminus.