An agency in the context of a novel is like a group of people who help the author sell their book. Imagine you made a painting and you want to sell it to someone. Instead of just putting it in your front yard and waiting for someone to walk by and buy it, you might go to an art gallery. The art gallery is like an agency for your painting. They help you get the word out about your painting and find someone who might be interested in buying it. In the same way, an agency for a novel helps the author find someone who might want to read their book. They might help the author edit the book, design a cover, and promote it on social media or in bookstores. It's like having a team of helpers who are all working to make sure your book is the best it can be and that people know about it so they can read it.