In blog settings, you can show/hide Post Meta. Post meta includes author public name, date of the article published and categories under which the article was published.
By default this is turned ON.

Single Post

The Post Meta is displayed on single post page as well. You can turn it off if you want.

• Author Box – it is displayed under the single post article below the content. Provides introduction or bio of the author. You can add/edit Author bio from your wp-admin, author profile section.
• Show Related Posts – Displayed related posts under single post page. You can control how many related posts it should display if you enable it.
• Comments – By default your new WordPress site comes with comments enabled. This is a global setup for blog posts only. You can still control comments on each page individually on page edit screen