Family planning operation for women is called tubal ligation or tubectomy. It means that the Fallopian tubes are ligated, thereby blocking the passage of sperm. In other words, sperm cannot reach the egg, and fertilization won't occur. It is a permanent birth control method, and for this reason it should be done only if one is sure not to have children in the future.
Learn more about this technique here: Tubal Ligation Procedure – Should You Get Your Tubes Tied?