What does the saying Zachra blue mean?

There is no known saying or phrase called "Zachra blue." It's possible you've misheard or misspelled the phrase.

Could you provide more context or information about where you heard this saying? For example:

* Where did you hear it? (e.g., a movie, book, conversation)

* What was the context? (e.g., what was being discussed?)

* What language is it in?

With more details, I might be able to help you figure out what the phrase means or if it's a misunderstanding.