The Blog page is a usual blog, formed from the posts which belong to categories created by you, which have tags and featured images that show in the post listings on the blog page. The blog page can have the sidebar on the left, right or no sidebar, and the contents of the sidebar, as described above, are set under the Appearance > Widgets. You can use shortcodes in the text editor while creating a Blog post content.
Blogs can be posted by someone who has access to the backend of the site with the admin or author role. Anyway, that person will be able to log into the WordPress panel and have a user profile.