Humans convey emotion and thoughts in conversation. We have mirror neurons that literally model an approximation of the internal mental state of the person you are talking to.

Facts won't stop a toddler crying for ice cream. But a clear unmoving boundary conveyed with love stops the intensity of their request and allowing them to have the sadness and anger at being told no and treating them with kindness and love even while they are expressing big feelings of disappointment creates a trusting, safe relationship.