Most small SEO edits, such as rewording a page title, only touch one page. A few changes are different: one mistake in one release can reach every page on a site. The ones Google's documentation points to are rules in robots.txt, noindex rules, canonical links, redirects and changes to URLs.
A sign-off is a short written approval for those changes only. It records what is changing, how it was tested, who agreed and how to undo it. This guide shows you how to run one, even if you are the only person in your team.