As to where this movie takes place, it takes place after the end of Dragon Ball Super: Broly*, but before the End of Z Arc, the final arc of the Dragon Ball manga, which was adapted as the final three episodes of the Dragon Ball Z anime.
The overall 21st anime film in the franchise, series creator Akira Toriyama returns to work on the film's story, screenplay and character designs. Planning for the film started in 2018 prior to the release of Dragon Ball Super: Broly, and that the film will feature an unexpected character, and its goal is to tell a "large-scale story", which will charter through, "unexplored territory in terms of the visual aesthetics to give the audience an amazing ride." Dragon Ball Super: Super Hero is set for an April 22, 2022 release in Japan, and is expected for a worldwide release in the same year.
[via Anime News Network]
* If you take into account the currently ongoing Dragon Ball Super manga, at least after the end of the Galactic Patrol Prisoner Saga, and likely after Granolah the Survivor Saga.