Abbie and Kaye are two young girls, classmates of Esperanza Cordero, the protagonist of the story. They are described as popular, privileged, and somewhat superficial. Esperanza initially admires their seeming freedom and ease, but eventually recognizes their shallowness and how their lives are ultimately constricted by their social position and expectations.
It's important to note that "Mara Clara" is a popular Filipino television series, and the characters you're asking about are not from that story.