This one's easy, right? Maybe it's too easy. How are you supposed to interpret the fact that a story called "Indian Camp" takes place in an Indian camp?
Well, think about why the story didn't just take place at someone's house. First of all, if that was the case Nick's father really couldn't have brought Nick along ("Oh, hello Mrs. Smith, do you mind if my young son stands in the corner and watches while you have a baby?"). At the Indian camp, the Indians don't really have a choice (take a look at Nick's "Character Analysis" for more on the roles of race, gender, and power in the story). In fact, the story is more about Nick and Nick's father than it is about the Indians as characters. So the Indian camp is essentially the place where the characters go so that all the action can happen.
The fact that the story begins with Nick traveling to the camp and ends with him leaving the camp isn't a coincidence either. In essence, a different Nick is going to leave the camp than the Nick that entered it. This new Nick now has knowledge of suicide, and with it, thoughts about his own mortality. This new Nick has also now seen things that the old Nick was reluctant to look at. So the Indian camp is not just a place, but a catalyst that has changed him.