宣 is a bound morpheme (b.f.) meaning 'to declare, to proclaim'. It appears as the first element in many formal compound words such as 宣布 (to announce), 宣传 (to promote/propaganda), 宣告 (to declare), and 宣誓 (to swear an oath). It can also mean 'to drain off (liquids)' in rare contexts like 宣洩, and is a common Chinese surname. As a bound form, it does not stand alone as a word; you must use it in compounds.