In common parlance, if something is to be taken with a grain of salt, it means that a measure of healthy skepticism should be applied regarding a claim; that it should not be blindly accepted and believed without any doubt or reservation. According to the Oxford English Dictionary “to take ‘it’ with a grain of salt” means “to accept a thing less than fully”. It dates this usage back to 1647.

Another meaning is ‘with moderation’, and it is related to the way someone uses something. It probably refers to the activity of cooking, where only a pinch of salt is sufficient to enhance the flavour of a dish. In this sense, using something ‘*** grano salis’ means to use it with moderation.

The phrase comes from Pliny the Elder’s Naturalis Historia, regarding the discovery of a recipe for an antidote to a poison. In the antidote, one of the ingredients was a grain of salt. Threats involving the poison were thus to be taken “with a grain of salt” and therefore less seriously.

so the phrase “taking it with a grain of salt” means you might not like what your gonna hear ,it may be hurtful for you to have to hear it ! So take it with a grain of salt !

or its probably not true