Complex sentence: In quantum mechanics, particles such as electrons are described by a wavefunction, a mathematical description of the quantum state of a system; the probabilistic nature of the wavefunction gives rise to various quantum effects.
Split into simpler sentences: In quantum mechanics, particles such as electrons and are described by a wavefunction, a mathematical description of the quantum state of a system. It is the probabilistic nature of the wavefunction that gives rise to various quantum effects.