You can customize the text of various parts of the site, like for the search box labels, heading text, error messages, the intro text, and more. To do this, go to Appearance -> Theme Options -> Custom Text.
For the wording for the features list (in the Listing Detail page, next to the large slideshow image), you need to hand edit /includes/features.php. A future update will allow editing this text from Theme Options, but for now you must edit this file.
If you need to change the wording for things that are shown in the WP backend, like when you make a Listing post, etc., you need to hand edit the functions.php file. Just do a search for the word you need to change and you’ll find where to change it. Just be careful to not break the code.