Joomla!™ Administration - Global Configuration
The Metadata tab allows you to add meta description for your website as well as keywords - this information will allow search engines to easily index your website in their search results. Please, make sure to add meta information relevant to the content of your webpage.
The Mail tab contains settings for Joomla mass mailing function. It allows you to send newsletters to all your users. The default settings are correct and tested on the SiteGround servers - the only thing you may decide to change is the sender's e-mail address.
Changing the settings in the Cache tab may lead to security issues with user accounts (especially on publicly accessible computers) and are not recommendable.
The Statistics tab has three options. The most useful is the first "Statistics" and you can turn it to "Yes". The rest will collect large amounts of data which may slow down your site.
Please, find below information about the other options in the Global configuration tab:
We do not recommend changing the default Database, Server, and Cache tabs, unless you know what you are doing. Any incorrect setting in these sections could render your Joomla-powered website to be inaccessible.