This is a blog page excerpt text. You might need to enable the excerpt field in screen options first when editing the page you have set for your website blog.
The style guide provides you with a blueprint of the theme’s default post and page HTML styles. This post also displays automatically generated table of contents. Intro image is disabled on this post.
This is an example of image post format. You should really set post featured image for image post format or the first image found in post content will be used.
This is an example of gallery post format and also an example of disabling post comments. You don’t really need to set post featured image for gallery post formats, it’s up to you.