Hello, having sun in 12th house is rather weak position, but it is better if it is in fire sign (especially Leo like in you chart) because Sun rules Leo, it gives it strenght and vitality to shine through and act even in rather foggy, passive and introspective place which is 12th house (subconscious, ruled by Pisces). Venus is a beneficial planet, so this tight conjunction is good for valuing yourself and ability to enjoy life. Even though your sun is in 12th house, I'd say it is positioned quite nice. I think you believe in yourself, sometimes to a fault, because your Sun squares Jupiter. There is a danger of underestimating "enemy" or overestimating your powers. You probably need your space and hate being held down or told what to do. Because of the square and the Sun-Venus conjunction, you should watch out for overindulgence in all matters. Finally, your Sun-Venus conjunction is squared by Pluto. I also have Sun-Pluto square (also Leo here, yay!
) and this is sorta hard to realise, but there can be deep seated dislike of authority, destructive or even self-destructive tendencies, so you should watch out for drugs, alcohol and such, it does not do you any good, especially having two planets in 12th house and strong Pluto like yours. So be aware of your dark side, it is not alway easy to keep it in check but it can be done and it is way to perfecting your soul.
I noticed that you also have T-square made of Uranus-Neptune conjunction opposing Moon and squared by Mars, it is quite dynamic, so check it out.