Primarily a photography style that features symmetrical composition of the main subject and favors highly saturated pastels. But not always. I'd never heard of this before but it looks quite interesting and there should be plenty of good subject matter for most of us.
https://accidentallywesanderson.com/
On the surface it seems interesting. Call me dense, but I'm not quite getting a grasp on what the subject matter is exactly. There are a TON of different images types, subjects, etc. on the site you linked. Help me out here.