Complex sentence: This is also reflected in mythology, where Parvati becomes a part of Shiva, and in iconography, where he often has two supernatural arms and she has just one earthly arm and his vahana the bull--not her lion vahana--often accompanies them.
Split into simpler sentences: This is also reflected in mythology, where Parvati becomes a part of Shiva. Shiva often has two supernatural arms and Parvati has just one earthly arm, and his bull "vahana"--not her lion vahana--typically accompanies them.