You will get this as part of the tutorial of using the Wraith's abilities to your advantage. In this case, connecting to their thoughts allows you to fill in the shadows of the Sauron's Army page. If you do this same ability against a Worm (green diamond with arrows circling one another) or Captains (skulled threats that are harder than normal Orcs and Uruks), you can learn more out about the target, too. Use this often when you can.