Vocabularies in the story book

My daughter is studying P2 in ESF. Every week , she will borrow two story books from the school. Usually, she loves to read these books. However, I found that she does not know the meaning of ALL the words in the story books. These vocabularies are quite difficult or uncommon to me. I even need to dig out the exact meaning from the dictionary.

On the other hand, my daughter can roughly understand and enjoy the stories in whole even some of the words she don't know. My daughter don't care about these difficult word and just go on reading the storybook and enjoy it.

Do I still need to explain these vocabularies to my daughter e.g squiggly, thicket, stampede