What are Google Fonts?
Google Fonts (previously called Google Web Fonts) is an interactive directory of free hosted application programming interfaces for webfonts. It was launched in 2010. Many of the fonts are released under the SIL Open Font License 1.1, while some are released under the Apache License; both are free software licenses.
In normal speak: Hundreds of free, open-source fonts optimized for the web. Just 3 quick steps between you and a good lookin' website!
How do you add them to your store?
In the head tags of your theme you may find this script:
<!--Google Font-->
<link href='//fonts.googleapis.com/css?family=Source+Sans+Pro:100,400,300,600,800' rel='stylesheet' type='text/css'>
1) Go to http://www.google.com/fonts
2) Choose a font you find visually appealing.
3) click "Add To Collection"
and then
Scroll down and copy the code and place it in your head tags.
Note: take out the http: to make it work.
This can be found under Themes > Edit Theme > Head Tags.
You can also place the following into your CSS under Themes > Edit Theme > Global CSS Editor:
Here are some examples of some cool fonts:
For more info on styling and other cool tricks you can do, check out Google Fonts: Getting Started