It's a book by Stephen King, titled 'Pet Sematary', and it's about a graveyard for pets that has been established over time in one town. I believe it was actually established in the 1800's.
One of the earliest kids to bury a pet there made a sign for the graveyard, but didn't know how to spell "cemetery" correctly, so they spelled it "Pet Sematary". That then became the "official" name of the graveyard, and the title of the book and movies is just referring to that sign and name.
1 up, 3y
I’m kinda mad it’s R because I’m turning 13 in two weeks and I hear it’s nto really scary
3 ups, 3y
But that's the actual title of the movie! It's misspelled on purpose!