The Export / Import tab allows you to export the pages you create into a single file, called a LAR (Liferay Archive). You can then import this file into any server running Liferay, and all of your pages will be copied. This is a great way to take your content from one environment (say, a development or
QA environment) and move it all in one shot to your production server.
This is also a good way to back up your site's content. You can export it to a specific location on your server which is backed up, and if you ever have to restore your site, all you need to do is import the latest LAR file. One limitation on LAR files, however, is that they are version dependent, so you can't
use an export from an old version of Liferay and import it into a newer version.