Complex sentence: Tonality describes the relationships between the elements of melody and harmony-tones, intervals, chords, scales, and the chromatic gamut; but particularly those types of relationship that are characterised as hierarchical, such that one of the elements dominates or attracts another.
Split into simpler sentences: Tonality describes the relationships between the elements of melody and harmony-tones, intervals, chords, and scales. These relationships are often characterised as hierarchical, such that one of the elements dominates or attracts another.