The Sun and Pluto are two very different Kings. The Sun, center of the universe, is pure ego energy. He is life, light and clarity. Pluto is the King of the Underworld and rules death and transformation. He blows right through the ego and gets to the heart of the matter.
The Sun in Aries squares Pluto in Capricorn today. To me this says a conflict (square) between the established (Capricorn) and the new (Aries). We have the child like, confident Sun in Aries running up against a rather grim Pluto in Capricorn.
So there's a power struggle here. Being forced to let go of or say hello to your demons so you can evolve. Choosing life over death or depth over superficiality. A square indicates that there is no easy outcome. You have to fight to reach an acceptable conclusion.
You'll be feeling this conflict intensely right now if you have planets between 6 and 8 degrees Aries, Capricorn, Libra or Cancer. The transiting Sun and Pluto will be triggering issues involving power so you'll probably be feeling tense, edgy, restless and not sure what to do next. The key with this standoff is to look at what needs to go and what needs to emerge. Is a change of boundaries (Pluto in Capricorn) affecting you in some way? Is someone's will taking center stage (Sun in Aries)? Is an opportunity (Sun in Aries) interfering with a transformation (Pluto in Capricorn)?