The title information refers to the text in the <title> tag. It will appear at the top of each page. If you delete this line, your journal defaults the title to your journal OR the "journal title" that you give it on the Customization Page.
The favicon information refers to <link rel="shortcut icon" href="http://i51.tinypic.com/dot7gy.png" /> which will replace the Tweak icon on your browser's information bar. If you delete this line, Tweak will show up instead.
The meta information refers to everything in the block with the meta tag. The description and keywords are what search engines will use to categorize your page. You can delete these two lines if you don't want to bother with them. However, I ask that you please do not delete the author line as it links back to this community.