Well, it could be about various things. Maybe it's a story that takes place in the remote countryside, like the adventures of a hiker exploring the back country. It might involve encounters with wild animals, beautiful natural scenery, or the challenges of surviving in a less - inhabited area.
In a 'back country story', it could also be about the history of a particular back country region. It might include tales of how the area was settled, the struggles the early settlers faced, and how the place has evolved over time. For example, it could be about a mining town in the back country that boomed and then declined, and the stories of the people who lived through those changes.