|1.||with a grain of salt|
Meaning to take something lightly, especially with advice. To be skeptical.
Take a novice's advice with a grain of salt.
Anything free should be taken with a grain of salt (there's no such thing as a free lunch)
|2.||with a grain of salt|
When qualifying advice: For example your mother is always cold and thinks that you will be too. Therefore she always tells you to take a jacket with you. Perhaps she gets cold easily and you do not. If you want to communicate this different subjective preference, use this phrase.
Take your mother's advice to wear a coat "with a grain of salt"