This is a widget area, so you can set a message and drop in a shortcode button, an image, HTML or pretty much anything else you wish. If you don't set anything here it completely disappears as a section. Nice.
This text is set easily in the theme options panel. You can highlight how awesome your blog is.
This is an example displaying a standard WordPress gallery set at the top of a post. This text will stop displaying on the blog index page wherever I decide to place a read more tag.
Welcome to the good ol’ standard post format – you can add a featured image or not, type your post and link to articles and even place inline images or a fancy lightbox powered standard wordpress gallery to your post.