If you're a Star Wars fan, you should have no problem diving right into the universe of new Disney+ series The Mandalorian, which picks up roughly five years after 1983's Return of the Jedi and 25 years before 2015's The Force Awakens. But even if you've never seen a Star Wars movie, you can still watch The Mandalorian without having trouble keeping up. As showrunner Jon Favreau told The Los Angeles Times, "It's an invitation into [Star Wars] in a very pure way. It's the first time since Episode IV where it's inviting people into a whole new cast of characters that doesn't require any prerequisite understanding of the world."
There is, however, a huge, giant, unavoidable caveat to the idea of watching The Mandalorian without having seen the Star Wars movies: you should watch them anyway. Doing so will only enhance your Mandalorian viewing experience, and hey, if you like the show, you'd probably like the immensely popular franchise that pre-empted its existence, too.
The official description of the show puts this into perspective:
"After the stories of Jango and Boba Fett, another warrior emerges in the Star Wars universe. The Mandalorian is set after the fall of the Empire and before the emergence of the First Order. We follow the travails of a lone gunfighter in the outer reaches of the galaxy far from the authority of the New Republic."
You see, anyone could follow a story about a lone gunfighter on a fictional planet, but it would be even better with context. Without the Star Wars movies, "Jango and Boba Fett," "the fall of the Empire," and "the emergence of the First Order" are all totally meaningless. Watching the Star Wars films (or at least the original trilogy and reading summaries of the prequels, if you must) will show how The Mandalorian fits into the bigger picture and allow you to understand more of the references. (How else are you supposed to know the true significance of people being frozen in carbonite?)
But if you don't want to do that, to put it into the most basic terms, The Mandalorian takes place after Darth Vader was taken down (surely everyone knows Darth Vader), but a couple of decades before the stuff happening in the current trilogy. The show doesn't directly involve any characters from any of the movies.
Setting The Mandalorian even further apart from the Star Wars film franchise is the fact that "Mandalorians" — people from the planet Mandalore — aren't mentioned in the films. Instead, they come from the Star Wars expanded universe, which includes books and comics not considered canon. The character Jango Fett — who is featured in Episode II — Attack of the Clones — has been established as a Mandalorian, and his "son" Boba Fett, who's featured in the original trilogy, is associated with the group, too. (However, because Boba is actually a clone, he's not technically a Mandalorian, and as CNET notes, Jango is not always considered a Mandalorian, either. It's complicated.)
If this is all still sort of confusing for you, then that's reason enough to watch the Star Wars movies before watching The Mandalorian to get a better understanding of the galaxy we're working with. Otherwise, jump right in, but just know that a few things may go over your head.