What is the meaning of word zopa that Sharon Cameron uses in her book called forgetting?

There is no character named Sharon Cameron or any mention of the word "zopa" in the book "Forgetting" by Sharon Cameron. It's possible you're misremembering the author or the book title, or perhaps you're thinking of a different work.

If you can provide any more context, such as the specific passage where "zopa" is mentioned or any other details about the book, I might be able to help you understand its meaning.