Literal translation
Neither speaks nor whistles
Meaning
he or she says absolutely nothing
Explanation
This expression describes someone entirely silent, giving no sign, verbal or otherwise, of what they think or feel. The image pairs two ordinary ways of expressing something with the mouth, speech and whistling, only to deny both at once: the person in question does neither, remaining as mute as a stone. From the neutral observation of total silence, the expression slides toward a harsher judgment, that of a closed off, sullen or even boorish person, incapable of the slightest mark of sociability that a word or a simple whistled signal would provide. It is used to complain about someone who expresses nothing, does not answer, does not greet, leaving the other person in complete uncertainty. The register is familiar, often tinged with reproach, used to call out a coldness or rudeness felt as a lack of consideration.