Hertz is a wavelength, not a bandwidth
WTF????
You have contadicted yourself..

Hertz is a unit of frequency.. bandwidth of a rf or audio signal is measured in Hertz

With a Monitor or television.. the refresh reate is the number of time the image on the screen is refreshed persecond (hence the dmorgans correct statement)

refreshrate is the number of time the image is redisplayed on the screen
framerate while it is almost the same thing it is the number of time the images changes persecond.

The human eye is able to tolerate very low frame rates down to some 7 to 10 frames persecond. The eye/brain will at low framerates notice the flicker (flashing/strobing effect) but still percieve the motion in any displayed animation.
The higher the frame rate the less perceptiable the flicker is to the brain..
Basicly your frame rate can not exceed your refresh rate, it is best if refresh is higher than framerate for television, standared tv this was.. framerate = 30hz, and field or refresh rate=60hz... the larger displays and HD sets run refresh rates of 120hz (I think..in OZ it is 25/50 and 25/100Hz) ... you will note here that the refreshrate normally is a full multple of the frame rate.

SO.. for smooth display of motion images.. the higher framrate is best
for low flicker from even a static image.. the higher the refresh rate the better

Oh.. just realisd.. why refresh?

In a crt.. the image is formed by a beam of electrons (per colour) scanning across the screen from left to right and top to bottom during the right to left transitions the beam is blanked as also during the bottom to top.. by the time the beam returns to its starting point the image at the top has faded (phospher does have a latency some are higher than others) so the image is ready to be redrawn..

With LCD's The image needs to be blanked between frames so that the fresh image (any changes from the previous) can be displayed without artifacts.. (LCD ghosts) I will admitt that i have run a stroboscopic test on some LCDs with a static image and did not notice a interferance pattern.. but ost I have seen will ..so yes they do have a refresh rate..
With LCD's the latency was a stumpling block with gamers for a considerable time..