frequency is measured in hertz. one hertz is one cycle per second. the more cycles per second, the higher the frequency. the higher the frequency, the higher the pitch or range of the sound.
bass, like from subwoofers, is usually under 100Hz (hertz)
vocals in music are in the midrange of audible sound, usually between about 500Hz and 8000Hz or 8KHz. (1KHz is 1000 hertz)
treble, like crashing symbols, shrill sounds, chimes, and so forth are in the higher frequency range for human hearing, which is above 8KHz.
human hearing range is 20Hz to 20,000Hz on average.
frequency is usually measured on the X axis of a graph. The Y axis of that same graph would represent amplitude, or volume.