Experiment in using a severly limited colour palette in a limited area in an abstract fashion, then building a scene out of it. The red here was deliberatly intended to look almost alien, out of place - that centre of the sun tying in only to the red trees, the yellow of the sun matched in the tree's highlights. Experimenting with strong colours on a fairly netrual background.
Those bits underneath are playing around with color mixing and comparing how colors laid adjacent on the canvas play off each other.