知事 is a historical and modern administrative title. In imperial China it referred to a county magistrate (知县), and in modern Japan it is the term for a prefectural governor (知事). The other glosses in the source — 'sensible' and 'begin to know things' — are not standard uses of this compound; they likely confuse 知事 with the verb 知事 (to know affairs), which is archaic. For HSK 7 learners, the relevant sense is the official title, used in historical Chinese contexts and contemporary Japanese contexts.