A Transient is a simple way of storing cached data in the database temporarily, by giving it a custom name and a timeframe after which it will expire and be deleted.
Transients are useful when pinging another API (i.e. Wordpress, Instagram, twitter), and saving data for a set period of time.
Once the module is installed, you will find a tab under Utilities. This batch list is only used for debugging. You can view transients here, and delete them.