I believe this phrase means the following.....In the process of growing and maturing everybody learns, not just from home, not just from parents, but also from friends, neighbors, teachers....because learning is a process of observing and absorbing. A person can raise a child in one particular way, but that child will be influenced by his/her surrounding by no less....therefore....to raise a child the way one would want him/her to turn out satisfactory..ofcourse according to that person's standard....is by finding the right environment most suitable for that person....and raise his/her child there.....because teaching is ultimately...not through words.....but rather a way of life.
And vice versa from the above....it takes a child to raise a village...because wisdom is not necessary always come with age....sometimes...the best lesson learn comes from the simpliest thing, a single word, or just a look.....it all depends on the level of observation and openness from the perspective person.......
Those are just my thoughts....if i'm wrong.....please correct, thank you =)