Real-time campaigns are time-based trigger messages. If a user complete one action, but not another within a given window of minutes, hours or days that you explicitly mention, Kahuna will send a message to that person.
Conversion Push is the first kind of real-time campaign created by Kahuna. It is always running in real time, searching for users who have done X but not Y in a given period of time. You can layer additional filters from the Event and Attributes list to create additional targeting criteria.
For information on how to create your own Conversion Campaigns, please refer to this How-To Document!