"Show don't tell" is one of those writing maxims that gets thrown around with little explanation. Scribophile Academy has a good article on it here. It's true that "telling" the entire way through your story is uninteresting and doesn't immerse the reader in your story. On the flip-side, "showing" every. single. thing. is very time consuming and not always that effective - especially if you've got a limited word count to work in.