You probably want as many people as possible to see your awesome publication. A simple link can be put inside a newsletter of course but you also want to be sure people can find your magazine on Google and maybe you want it to go viral on social media.
The meta tags that show a title and short description of your publication can be created on three levels. A total setting in the interface for the platform-wide publications. You can create other meta description on publication level in the publication settings or even create special title and text on page level in the page settings.
In the interface, you can show buttons to your own social media accounts and people are able to use links to share your publication on Facebook or Twitter. Settings for your own account and activation of the sharing buttons can be found in the Interface options inside the settings page. The title and text that is shown in a post can be set by changing the META information of a page, publication or platform. The small picture that's shown can be changed per page in the page settings.
To check what links to social media will look like you can test them with these tools: