Note that in British English, we say “to take it with a pinch of salt” (une pincée)
Have you ever been criticized for something at school or work? It is hard to hear something critical from a boss or a teacher, and it can make you sad or angry. When you get home, your family or friends tell you not to worry and to take it with a grain of salt.
To take it with a grain of salt means to not take something too seriously. Sometimes, it is good to take things with a grain of salt because worrying too much can make us sick!