One may have read about the 3 kayas or bodies of a Buddha and still come off not even an iota nearer to the understanding. Nothing can beat hearing it from a great teacher like His Holiness who offered a very clear differentiation of the 3 kayas.
Part 1: Nature of Mind, Dharmakaya
Part 2: Qualities of Sambhogakaya
Part 3: Body of Emanations, Nirmanakaya 1
Part 4: Body of Emanations, Nirmanakaya 2
Part 5: Guru Padmasambhava
Part 6: Conclusion - Sole purpose of Bodhisattva Path