Harmony is the result of more than one pitch or note sounding at the same time.
The relationship  between any notes that are sounding together makes the harmony (texture).
It is one of the basic elements of music, but  is not as basic as some other elements,
such as rhythm and melody.
You can have music that is just rhythms, with no pitches at all.
You can also have music that is just a single melody,
or just a melody with rhythm accompaniment.

PITCH is the quality of the sound with which we can create harmony.