@loukrismark Thanks for your message, and we certainly understand how that could cause some confusion.
When you say ‘the post title’ I’m assuming what you are referring to is when you first start creating a page in WordPress and your enter a title for it, such as in the image here. That title is essentially the title of your content, which is meant as the title that the site’s user’s read to get an overview of what the page is about. However, the actual HTML tag that title is, is <h1> which is the first header, like in an outline. And H1 is so important, you should only have a single <h1> tag.
Now, what we call the ‘SEO Title’ is the title that get’s read as metadata by Google. It’s not visible as content on the page that the user sees. We call it the ‘SEO Title’ to try to draw the distinction that it’s the title that is both read by a Search Engine, and displayed in it’s results. What we call the ‘SEO Title’ in the plugin is output as the <title> tag within the <head> part of the document, which is not what user’s see, and is mainly to be read by search engines.
As for best practice, you can find a guide on to craft the best page titles for SEO purposes here: https://yoast.com/page-titles-seo/
