It is not Spanish but English, but it is used a lot in our language in the environment of film productions, serials, novels, any story that has characters. In principle it means "turn on the outside", and refers to a version that emerges from a story, with some of its secondary characters for which a new story is created. It also has use in other areas, such as "accessory operation, derived from another main one". See English/spin ("spin, rotation"), English/off ("on the outside" [from the main story]).
