From thekeywordacademy.com: Before we can talk about how to optimize the body text of the page you’re working on, we should probably define what body text is. To put it simply, body text is the text that you can see on a web page. Everything you can see on this post would be considered to be body text.
The technical explanation of what body text is would be everything that appears between the opening body tag, , and the closing body tag, , in the code for the page.
Bloggers don’t really need to worry about the technical explanation – you can think of body text as a combination of your post title and the main body of your post, or as the text that appears on your blog’s homepage.