what can you say?; what more is there to say?
A rhetorical, somewhat literary expression of exasperation or resignation. Used when the speaker feels that words are insufficient or that the situation speaks for itself. Often follows a statement of an obvious or extreme fact.
こんなに証拠がそろっていて、何をかいわんや。
With this much evidence, what more is there to say?
His attitude is simply appalling; what can I say?