It is the ability to know what to do in a social-interpersonal situation.
(It is not the ability to analyse social phenomenons such as crime, divorce...)
So each social situation is a problem that requires solution. I can say that my logics/reasoning intelligence is strong-I am completely confident about that. But the current social intelligence is not so good-just above average. It is not enough to achieve my goal. Now let me be straight: I want to get excellent grade on this intelligence: as strong as logics/reasoning intelligence, say top 4% of population.
The good news is this intelligence can be cultivated( logics intelligence is not). Obvious sources to learn are: books, novels, movies. The difficulties may like in practice. 2 places to practice: practice in my mind and in reality.
We are always conscious of a logics/reasoning problem when we encounter one so we mobilize our intelligence to solve it. It may not be so obvious for social problem. So stay alert. I think this is not a big problem for me now. This step has been passed.