A developmental process, independent of morphogenetic (shape) change, that is required for the hypoglossal nerve to attain its fully functional state. This motor nerve innervates all the intrinsic and all but one of the extrinsic muscles of the tongue. [ GOC:cls http://purl.obolibrary.org/obo/go/references/0000021 GOC:dph https://www.worldcat.org/search?q=bn%3A0838580343 GOC:dgh GOC:jid ]