The purpose of the section of this story (ALWG) is to show how far Ishmael has drifted from being a boy and how he's turned into a monster that doesn't think twice about killing or the cruel things he is doing.
This particular scene is on page 151 in chapter 16. It is about when Ishmael's team had captured rebel hostages and tortured them by stabbing them in the legs, beating them up, making them dig their own graves (shooting the ground near their feet, or them if they slowed down), and burying them alive. The cruelty in this scene makes the reader reflect on when Ishmael had a childhood and was happy and was just a kid.
Hehe!! you will be killed! But first, we will hurt you like you hurt our families. we hate rebels!!
Oh No!! We're captured!!
Time for the torture!!
Now its time to dig your graves, and if you slow down, we'll shoot you!! Mwahaha
why did you stop?! Get back to work!! *shoots gun at hostage*