The basic concept of wormholes isn't massively hard to understand - someone invents a thing which allows humans to travel vast distances in space by bringing two distant points closer together. I have to point out right here that my knowledge of physics is limited to some GCSE experiments where the whole class held hands and the teacher gave us an electric shock (which I'm not sure would be allowed these days), so please refer to wiki if you want to know actual scientific stuff about wormholes.
But films. So when the plot of a film requires characters to travel a really long way in space and they don't want the actors to have to pretend to be a dessicated corpse by the time they get there, the scriptwriter will have the actors do a thing which I now call Wormholes 101. Because people who watch science fiction films are obviously too simple to understand a sentence or two about the theory behind wormholes, they explain it by taking a piece of paper, folding it in half, then punching a hole through both halves with a pen to demonstrate how a wormhole would theoretically shorten distances in space.
The pen is the spacecraft.
Contact, Event Horizon and Interstellar, to name but a few, have all employed Wormholes 101. Though given some of the stuff that happened in Interstellar, explaining a wormhole would have been the least of any concerns about the limits of audience comprehension.
As you can see from the picture, I created my very own pretend wormhole while humming the theme to 2001: A Space Odyssey.