The copyright page is for your own protection: if somebody wants to use your intellectual property, they have to know how to find you!
A copyright page could be as simple as your name (or your publisher’s name if you have one), the copyright symbol and the year:
© John Smith 2021
If you are your own publisher, you don’t have to invent an imaginary publishing house. You can just publish under your own name, or even under your pen name or author name. If you use a publishing service to publish your book, still use your own name on the copyright page: you are the copyright holder.
You can also include a legal notice:
Published by John Smith
© 2021 London
All rights reserved. No part of this book may be reproduced or modified in any form, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher.
This text is fairly standard across books and publishers but you can tweak it as you would like to.
You can also use your copyright page to display your ISBN if you have one and credit everyone who helped you: editors, cover designer (and the owner of the cover image).