What is the function of utterances of this kind? ... their function is a learning function ...
in the sense that they contribute to the child's learning about the
environment.
... so we can interpret this mathetic function as arising from a
combination of two other functions, the personal and the heuristic. (Halliday, M.A.K. (2003). The language of Early Childhood. London: Continuum. p. 80)