As an example, picture a self-publishing coach, or book publishing coach much like a general contractor for building a home. Consider that a book project requires a full time effort for many months or years, depending on the scope of the project. Therefore, a good publishing coach will save more money and time than a writer is likely to spend doing it themselves, with costly mistakes.
All in all, your book coach coordinates, schedules, and budgets all services and activities to build a published book. However, most people cannot do these technical tasks, so they turn to specialists. Yet, often they hire novice workers, which can become an overpriced nightmare. Remember, You do no know what you do not know! Lastly, see Self-Publishing Coach–Why I Do it and FAQ Self-Publishing Questions.