This will introduce you to the Bandit Camp side missions. They’re essentially just sweep and clears, much like other open world games, where by clearing them out you’ll unlock a fast travel point and a merchant. This particular mission is worth doing because you’ll unlock a merchant that sells maps for some of the collectibles scattered around the map. To pick this one up, talk to Nil, who’s sitting at the side of the road on your way towards the main mission waypoint marker.
Once you’ve talked to him, make your way to the waypoint marker just outside the bandit camp and talk to him again to start the mission properly. Your goal is simply to kill every bandit in the area, so using your Focus to tag them before you go in is a good idea. The main thing you need to watch for is the bandit’s setting the alarm off and your getting overwhelmed from sheer numbers. Nil will be providing backup on this one, but don’t count on him, he’s not hugely useful. The best bet is, much like many of the games in a similar genre, stealth your way around as long as you can until you get spotted, then just go hell for leather to kill the rest.
Once the camp is clear, have a chat with Nil, and also make sure you visit the merchant for those maps, and you’re done.