用英文翻译：“这是个不能说的秘密”

This is a secret that can't be spoken out.

This is the secret being able to not speak.

This is a secret that cannot be shared.

再教你个最cool的说法：

This thing, just between you and me.

This is a secret that can't be spoken out.绝对对的 拉~~

A secret can not tell

this is a unspeakable secret