Tell me about some of the general significations of the sun.
Why might it be not so positive in this chart?
Some general significators of the Sun that I can think of are leadership, mastery, success, "being seen", power and honours.
Sun in this chart rules the 2nd and is placed on the ascendant. The negativity would come in because it is going towards a trine with Mars which it will receive in it's fall. Mars won't like that and so will reject whatever the Sun is trying to advance in the chart. Mars rules WS 10 and is domiciled. This may mean that this job of his won't likely to result in much "fame" and honours and the money would also be lackluster.
That's where I am from looking at the sun atm.