Math and numbers in general. I have hyperfantasia so the voice in my head is completely self directed and language is otherwise only external, I read whole words I don’t read letters, when I learned to read it was all at once essentially, like flipping a switch. Numbers don’t have anything visual I can attach to them and don’t exist holistically, I have to look at each number not the whole set or problem or algorithm at once so it’s very foreign to how my mind works. Ideally I could just do everything in geometry because I do have something there to translate to my visuals only brain but as is I just really struggle with math and reading numbers.