Graph search is the new features on facebook which is still in the beta stage. it is not available for everyone.
Through this awsome feature you can search for the people based on your intrests,places,activities and lot more
For example.
If you just enter " people who like playing cricket ", it will show you the list of your friends who love to play cricket in real time.This makes you easier to explore people with common intrests and have fun.
In not time we can see Facebook graph search on everyone profile. You can get more updates about Facebook graph search from here. Facebook Graph search