Lights

1.  “He gets all teary telling about the good times they had together, how her brother made the war seem almost fun, always raising hell and lighting up villes and bringing smoke to bear every which way.”

Light up means bringing happiness.

“A nature hike, they thought, not even a war, so they went off into the shade of some giant trees—quadruple canopy, no sunlight at all—and they were giggling and calling each other motherfucker and playing a silly game they’d invented.”

“Up in the canopy there were tiny white blossoms, but no sunlight at all, and I remember the shadows spreading out under the trees where Lemon and Rat Kiley were playing catch with smoke grenades.”

Sunlight means peace, hope and wished to end the war.

“And if nobody chickened out, the grenade would make a light popping sound and they’d be covered with smoke and they’d laugh and dance around and then do it again.”

Light is an adjective here, meaning quiet, not loud.

“There was a noise, I suppose, which must’ve been the detonator, so I glanced behind me and watched Lemon step from the shade into bright sunlight.”

“Then he took a peculiar half step, moving from shade into bright sunlight, and the booby-trapped 105 round blew him into a tree.”

Sunlight is the light come from an explosion, as sharp as the light from the sun. Lemon stepped into sunlight means he died in the explosion, but also light is a metaphor of a relief from the war and going to the paradise where is peaceful.

“All the while the baby buffalo was silent, or almost silent, just a light bubbling sound where the nose had been.”

Light means not loud, which indicate that the water buffalo was almost dead, also reflect Rat was so cruel to shoot the water buffalo.