This painting is talking about the unity of elements that make One single complete entity.
The painting can be viewed in several ways:
1. Father (the upper figure), a mother (middle figure) and a child creating one family.
2. The elements of sky/air represented by the upper figure, earth represented by the middle figure and water represented by the lower figure creating one planet-earth.
3. The upper figure representing the past hovering over the rest of the figures as if dissolving but still present in our minds, the middle figure representing the present who's nourishing the future - the child figure which is dependent on mother's care and actions which will determine how he will be. All those elements create one life time / world existence.
Of course there may be additional meanings in which this painting can be viewed so feel free to open your mind to other possibilities and even add them in comments if you like...