I read this in a blog as a profile description for a girl. The phrase is "princess of all things shoes" What does this mean?
The phrase all things + noun is an informal way of saying "everything about or pertaining to [noun]." Thus a Youtube channel about all things Barbie, the fashion doll by Mattel, or a restaurant in Wichita KS named All Things Barbecue.
A variation labels a person a lover of all things [noun], or to express special expertise, fame, or great enthusiasm for something, the [noun of high rank/status] of all things [noun]. So a female academic becomes the doyenne of all things Byron, famous designer Diana Vreeland is the grande dame of all things fashion, or a particular gelateria in Lucca, Italy, rather than a person, can be proclaimed the king of all gelato.
So the woman described as the the princess of all things shoes really knows shoes, loves shoes, and loves to shop for them.
It means she's the leader, the fashion guru, on the shoe front. An enthusiast about everything to do with shoes. Probably has a vast shoe collection as well.