"(With) a grain of salt," (or "a pinch of salt") in modern English, is an idiom which means to view something with skepticism, or to not take it literally.
网络释义
1、有保留地
...black-out curtain 暗幕，黑幕grain of salt 有保留地second banana (喜剧表演中配合主角的)第二喜剧演员，配角，次要角色；次要人物；副手,第二把手 ...