my text book says
"Miso soup is a typical, everyday Japanese food."
I don't know why there is comma after the word typical.

Is it OK that we write "Miso soup is a typical everyday Japanese food."? (no comma)

查看翻譯

The comma is a convention. When we use two adjectives in a row that both describe the noun in the same way and so could go in either order and we don't connect them with "and", then we use a comma. You need to have the comma there for it to be correct. "typical" and "everyday" here both describe "Japanese food" in the same way and it would be equally acceptable to write "everyday, typical Japanese food", so we use a comma between them.

https://www.grammarflip.com/curriculum/commas-b... explains with other examples.