This is a year of language explosion. Your toddler understands many more words than he can say. The number of words he knows and uses is directly linked to what he hears.
The way parents and caregivers talk to children has a significant effect on the child’s I.Q., literacy and academic success later in life. The frequency and quality of words a child hears during her first three years of life are critically important in shaping language development. HART AND RISELY, 1995