This occurs during the Himmel Street "parade" of sorts, where Liesel is being introduced to the community after arriving at the Hubermanns' home. She's nervous and unfamiliar with her surroundings, so she finds solace in the ring of her deceased brother, Werner, which her foster mother, Rosa, had given her.
This small act of symbolism is important because it foreshadows Liesel's future as a "book thief" and her journey to find solace and connection in the face of immense loss and hardship.