Authors are proud of their work…as they should be. They have spent many hours perfecting the text, checking the spelling, grammar, and punctuation, and reacted to comments and corrections from their beta readers, but that’s usually not enough.
Friends and beta readers will do their best, but they have their own work, family, and other obligations to consider. They can probably only get to your book when they can.
Professional editors spend entire working days, even weeks or months, on a single novel. They work until they have a thorough understanding of the story and are in a much better position to point out contradictions in characters’ behavior, inconsistencies in syntax, and irregularities in the flow and formatting.
None of this is done in isolation. Editors and authors have to work together. It’s the editor’s job to be honest with the author when suggesting improvements (such as rewriting, restructuring, or cutting sections) while respecting the author’s message, meaning, tone, and style. Both the author and editor have a shared interest in producing a work that gets and keeps the reader’s attention. But, even beyond that, with experience and knowledge of the book-selling market, an editor can suggest ways to take your novel in a direction that might better attract the eye of a publisher if that’s what the author wants.