This stages comes in the life of infant at the development stages of 2 years old. It is all about self awareness where the child will be able to play around and develop the sense of identification and learning new set of languages from surroundings.
It is the stage in the development of the infant (by two years old) where "self-awareness" comes into play, Infants can identify themselves in a mirror as well as begin to use language to refer to themselves. Infants also become aware of the surroundings.