There are two interrelated ways to look at the play-time of a two-year-old. First, you might consider such activity to be work, in the sense that play is the work of a two-year-old. As two-year-olds spend their day playing, play functions as an opportunity for learning. The second way of understanding play is as a kind of freedom from work. That is, sometimes a person, especially a two-year-old, shouldn't have to work. If children happen to learn while they play, that is secondary because the real point of play is to have fun.