It means that he is a native of Cunaviche, a Venezuelan municipality in the State of Apure. Concerning Cunaviche . Cunaviche is the same as estuary and that is actually an area of the plain that floods and becomes swampy. Also therefore cunavichero can be an estuary or a flat and flooded terrain.
1º_ Relative to Cunaviche ( "river and parish of the Municipality Pedro Camejo, Apure State, Venezuela" ) . 2º_ "El Cunavichero" is the nickname of a character in the novel Doña Bárbara (Rómulo Gallegos, 1929).