Nudity in a film means that some of the actors or actresses are shown without their clothes on. Sometimes, the characters in the movie need to take their clothes off to make the scene more realistic, like when they are taking a shower or swimming.
But, since we don't see people naked in real life all the time, it's important to understand that filmmakers take a lot of care when they show nudity in a movie. They want to make sure that everything is done tastefully and respectfully, and they usually use special camera angles or lighting to make sure that the actors' private parts are not seen on camera.
It's also important to remember that nudity is not always appropriate for all ages. That's why some movies have a rating that says it's only for grown-ups or for teens who have their parent's permission. So, it's important to ask grown-ups before watching a movie with nudity, and to always respect the film's rating guidelines.