Isekai

This genre of anime usually starts out with the protagonist being transported to another world, usually a fantasy setting, where they must learn the rules of this new ‘world’…

And for you technical otaku out there…

Wikipedia: An “accidental travel” genre of light novels, manga, anime and video games that revolve around a normal person from Earth being transported to, reborn or otherwise trapped in a parallel universe or fantasy world, where they must adapt and/or assimilate into this new world, along with its new rules, new cultures, and new philosophies. This style of fantasy subgenre has dominated the young adult literature for decades, but recently Japan has coined a single word to sum them all up called “Isekai”