Search for one of the label you seek and you should get an idea of where they are. You can find out a little about the available companions by looking at the Encyclopedia by pressing the N key. Traits are separate stats that affect things like negotiations in quests. The labels indicate what base stats they have and what traits they have been assigned. Companions are specialised units that take a slot in your army, though what exactly they can do is initially unclear. Simply head into a large town or settlement and click the option available to travel to the tavern.
The most valuable people though will be companions, who are people you can assign roles within your army and who can be upgraded in similar ways to your player controlled character. Recruiting people to your cause in Mount And Blade 2 Bannerlord is key to achieving your goals, whatever they may be.