Creating a new world is hard enough. Then describing it in a story is a little like pretending that you have an alien penpal.
An alien would have no context or prior knowledge to understand the world that you are writing about. You don’t know what your reader’s life is like, so you can’t compare the things that are unfamiliar to them to something that is familiar to them. But you don’t want to get so bogged down in the details of explaining every little thing that you bore them.
For example, how do you describe cheese to someone that doesn’t even know what a cow is? Do you describe the texture and the flavor? Do you explain about mammals producing milk and how humans have domesticated cows in part for their ability to produce milk that humans can consume? Do you launch into a story about how cheese is cultivated and aged, and all of the different variations that can be produced? Or do you give them a list of all your favorite dishes with cheese, knowing that the alien won’t be able to understand “pizza” or “nachos” without also knowing what bread (the basis of pizza crust) or tortilla chips are?
We take the easy way out when we write fantasy stories. We write about Earth in another time period, or an alternate version of Earth, or a planet and culture that is very Earth-like. We use familiar terms like “cheese” and “knight” so that the readers can bring their prior knowledge to understand what we are talking about. And then we tend to adopt the culture that goes with these terms, some kind of pseudo-European medieval creation.
But if you want to break out of the mold, how do you express that to your readers without saying “my knights are different” and “this kingdom is not a traditional monarchy” and “no, no, these are not modern-day gender relations, but they’re not stereotypical patriarchal oppression either”. How do you signal that your world/culture is not a cookie cutter without bogging down your writing with constant exposition/infodumps?
Sometimes I try to pretend that I am writing to my alien penpal again. But then I can get too detailed in my explanations. I start going on about the history of cheese and the many different cultures that use cheese, without telling how the cheese actually functions in an individual person’s life. My revision process is a lot about “okay, now dial the exposition back”. But I also have to figure out how to focus on the right things that the reader needs to know to see and understand the daily life of my characters. And then I realize that I’ve also taken things for granted, and I need to add more exposition, just in the right place.