What is a "pipel"?

Although you may not find the word "pipel" in a standard English dictionary, you can get a sense of what it means from the novel Night:

In his "service" was a young boy, a pipel, as they were called. This one had a delicate and beautiful face—an incredible sight in this camp.

So, a pipel is a young boy who works as an assistant and gets certain rewards. We assume that these boys get their special positions by being very physically attractive and by being subservient to the older men whom they serve.

This particular "pipel" is one who serves the overseer at Buna, has a beautiful appearance that reminds the narrator of an angel, and suffers a terrible death as punishment for being involved in some kind of sabotage.

When you consider the existence of this "angelic" pipel, his own brutal behavior toward his own father, and his terrible torture and death, you start to understand the intensity of the narrator's despair and the confusing, chaotic nature of his struggle to maintain his faith in humanity.