Here is an example of the colophon page for my novel "Looking Back".
You want to state your copyright here. Note that you don't NEED to state the copyright in order to own the copyright. You automatically own the copyright the moment you write the work. It is fully yours. Still, you want to state it to reinforce that.
You want to list any design credits for the inside or cover of the book.
You want a statement here about how your book may (or may not) be used. If you're writing a work of fiction, you want the disclaimer that your book is not about actual people.
You want to state your ISBN number here. Note that an ISBN number is version specific. That is, the ISBN number assigned to your paperback version is different than the one assigned to your Kindle version. Those are different formats, so they get different numbers.
You probably also want a printer's key on here. A printer's key keeps track of which version the book is. That way if someone writes you to complain about a typo, you can figure out which book version they have in their hands.
Sample Book Copyright Page
Printers Key on Copyright Page
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