Finding a cycleable route from where you are to where you're going: maybe the most efficient route for a mile-long journey in town; maybe a tour across Europe.
Traditionally, navigation involves maps and possibly a compass. Today it's just as likely to be a gps unit, or an app on an iphone or android smartphone. Navigation questions might be about planning a route before you start, or finding your location when you're on the bike. They could be about techniques for identifying landmarks, about the meaning of road signs and markings, or about the devices you carry with you to navigate.