What’s “The Shining” really about?

I started going out with a foreign woman that I met in college. She’s really into horror movies and all that junk, but I scare too easy for that stuff lol. One of her favorite movies is “The Shining”, which I found out from a mutual friend. I really wanna impress her, so I was thinking of watching the movie, so we could talk about it on our upcoming date. However, I’m too scared to watch it lol I heard it’s really scary and a lotta people seem to love it. Can anyone of you tell me what the movie is really about?