I'm not sure if that quote is from Socrates or not, but I believe that it originated from his ventures. When Socrates went to see the oracle he was told that he was the wisest person alive. He told the oracle that this was not possible because he knew nothing at all. So in believing that the oracle was wrong he set out to find someone smarter than he was. He talked to politicians, religious figures, and commons in the city. He went back to the oracle and said that he talked to these groups of people, and while they claimed to know everything they spoke on, Socrates was aware that none of them knew anything. What he found out was, while no one knew anything, he was more intelligent for the very fact that only he understood that he knew nothing at all, thus he was the wisest.
Personally I believe this to be true. But I really don't bother to much with it because there is no true purpose beyond knowing that we are all ignorant. Everything we "know" is what we (mankind) manifested and defined. Every word in every language used to describe what we perceive through the senses was created by us in order to set standards for human communication and truth. The best philisophical example is the image of beauty and how "beauty" is non existant. What one person believes is beautiful, another will not, therefore that image is not beautiful, and there is not beauty. We know the sun is "hot" but we defined what "hot" is and can not know for certain this is true.
The Matrix pretty much covered it in the scene where they are all eating at the table, talking about the flavor of chicken.
Just know that we were brought into this world ignorant, and intelligence is based on retaining knowledge for a "truth" WE defined.