Okay, imagine you have a book that's all about a story of two boys who like each other in a special way. That's what gay pulp fiction is. Pulp means the paper used to make the book is not fancy and expensive, but instead it's more cheap and affordable.
In the past, people thought it was wrong for two boys or two girls to like each other, but some people still did. So, they might have wanted to read stories about other boys who feel the same way. These stories could be exciting, romantic, or scary.
Gay pulp fiction helped people who were gay to feel less alone and more seen. Now, many more people believe that everyone should be allowed to love who they choose, which is a very good thing.