Someone who's “looking for an editor” is most likely referring to the need for a copy editor. There are, however, a few types of editors to choose from, and it’s best to know what you’re looking for if you want to get your publishing budget set up accurately.
Developmental editors work with you from the very beginning. If you have a concept or a great story idea but aren’t sure how to execute it, a developmental editor can help you organize your thoughts, give suggestions to aid your research, and help you get a handle on the big picture.
Substantive editors enter the picture when you have a full text. Some beta readers are skilled enough that their summary resembles the evaluation of a substantive/content editor. They’ll spot when your writing isn’t clear, your characters are weak, when your plot has holes, and when timelines don’t add up properly.
Copy editors come into play when the text is nearly final—or as final as an author can get it on his own. This type carefully reads each sentence, correcting typos, spelling, punctuation, word usage, and grammar. They’ll alert you to stilted dialogue and inconsistent character details.
Proofreaders take the final look at your project. They ensure all the copy editor’s changes were implemented, and fix any typos that may have been missed during the initial copy edit.
Each type of editing comes with its own price structure, so it’s best to know what you need before rushing right out there. Many authors think they only need a proofreader, but actually need a substantive editor for a manuscript that’s not yet ready for even the copy editor. Know your strengths, but also recognize your weaknesses and set your budget accordingly.