Complex sentence: The superconductor in so-called Meissner state is an ideal diamagnet into which the magnetic field does not penetrate therefore the normal component of the magnetic field on its surface should be zero.
Split into simpler sentences: The superconductor in so-called Meissner state is an ideal diamagnet into which the magnetic field does not penetrate. Therefore the normal component of the magnetic field on its surface should be zero.