Happy to hear you are thinking about being an editor. I have enjoyed being an editor for over 20 years now.
There are almost as many roles for an editor as there are editors. I am a medical acquisition editor. My job is to find the next project my company will publish and manage those projects until they are printed and in the warehouse. While doing that I work with managing editors, development editors, production editors, copyeditors and many others. I have developed a bit of expertise in medicine, mostly understanding the specialed language doctors speak. My degree though was in journalism. I have friends who are math editors and physics editors. I have friends who edit pharmaceutical company submissions to the FDA. They have expertise in these areas.
My advise is to build expertise in something you really enjoy. It can be social work, gaming, animals, almost anything. Editors are needed in all areas. At the same time, work on your editing skills. You will want to learn the style your field uses. For me that is AMA. In other areas it might be APA, Chicago, or something else. You will want to be expert in grammar, spelling and all the normal editing areas. I will also mention that there are video editors, audio editors and many other kinds of editors. These can be awesome jobs for the right person.
The most important skill you need to develop though is the ability to communicate with others. Editing is intimately connected to people. When you edit someone's work, you need to be skilled in editorial and have the ability to help the writer understand why you made your edits.
Editing can be a wonderful career. Good luck.
Writing and editing in business fields tend to have better salaries than what you will find in journalism and publishing. It is important to be well read, keep up on your editing skills and write consistently.
Good luck with your plans!