The article’s title suggests that light might be what these girls are looking for. And, indeed, the light they find is important, as it can lead them to the dark places of war and evil. However, the light they find also carries with it a risk: it can be used for evil. This is what the article is trying to say:
The article is trying to say that light and connection are key to finding hope in the darkest times. These girls found a beacon of light that can lead them through any situation, and they are many of the many who have found hope in the times of darkness.
“All the Light We Cannot See” follows Marie-Laure, a blind French girl, and her father, Daniel LeBlanc, as they flee Paris during World War II. They’re intent on keeping a valuable diamond out of Nazi hands. They move to the seaside town of Saint-Malo, where Marie makes a connection with Werner, a German boy who’s been enlisted to monitor radio broadcasts for the Nazis. Netflix describes the story, which follows Marie-Laure and Werner for a decade, as “a story of the extraordinary power of human connection — a beacon of light that can lead us through even the darkest of times. “