天机不可泄露

tiān jī bù kě xiè lù

lit. mysteries of heaven must not be revealed (idiom); must not be revealed

I am not at liberty to inform you.

天

tiān

day

机

jī

(bound form) machine; mechanism

不

bù

no; not so

可

kě

(prefix) can; may; able to; -able

泄

xiè

(bound form) to leak out; to discharge; (fig.) to divulge

露

lù

dew