Question

how is pitch related to frequency of sound

Answer 1

high pitch means high frequency of sound
low pitch means low frequency of sound

Answer 2

The pitch of a sound you hear depends on the frequency of the sound wave. A high frequency sound wave has a high pitch, and a low frequency sound wave has a low pitch. For example, soprano singers stretch their vocal cords, so they vibrate more quickly as the air rushes by them, which creates higher-frequency sound waves that have a higher pitch.