What do you think of when you hear the phrase "good with people?" When a wine is good with steak, it means that both the steak and the wine taste better when enjoyed together. If you are 'good with people' that could mean that both you and they perform better when you work together.
"Good with people" should not be confused with charm or grace. Many famous leaders have, in the absence of any obvious charm or eloquence, managed to get people to produce at high levels. Some introverts fail to be influential; some extraverts fail to be effective. The most useful criteria for "good with people" is the performance that results when an individual is working with others: does the sum exceed the total of the parts? Or would they all have been better working from separate cubicles?
We are entering the season of networking: it's a perfect time to observe the difference between the people who are working the room and the people who are making the room work.