"Apps" is short for "applications" - they're programs (like computer programs, not TV programs) that live on your phone and do some pretty amazing things. For example:

Google Maps - With Google Maps on your kajeet phone (depending on the specific handset you have, it comes preloaded or you can download it for free), you can get directions, find businesses, zoom down to the street level, switch between map view and satellite photos and much more!

Note: Depending on which kajeet phone you purchased, your handset comes preloaded with applications you might find fun and useful. Check 'em out!