What is a metaphor in The Doll's House?

A Little White Owl (Metaphor)

While introducing the Kelvey sisters, Mansfield describes Else, the younger sister, as wearing a too-large white nightgown-like dress and having "enormous solemn eyes—a little white owl." In this metaphor, Mansfield uses figurative language to suggest that Else's large eyes and silent, observant demeanor make her presence akin to that of an owl.