Here is "my" interpretation. At the beginning, this picture appears to be somehow senseless, but if one researches more about the personality of the painter, the interpretation becomes clearer.
With these three colours which are the fundamental colours, all possible colours can be created. How the colours are put into space follow no logical order, because they are purely put into place by the pure sentiment of the painter, Piet Mondrian.
The picture is extremely reduced. There are insofar no human indentations in it. By reducing this picture so much that it does not anymore distract the observer by things which were created by random and only the framework is painted, there is a lot of free space for the divine in this apparently simple painting.