Electricity draw. If you are using 220-240V then the standard is 50hz. Countries that use 110-115V use 60hz as a rule.
Generally right, but he is talking about the Vertical Refresh Rate. The refresh rate refers to the number of pictures per second. This monitor most likely accepts 50 pictures per second at full resolution and 60 at lower resolution. And by the way: this monitor is very low quality, even refurbished.
I probably should have been more verbose. Noidea is correct based on the information presented. I looked at the manual and realized that Tiger Direct pulled the wrong information and put it in the vertical refresh column. Most likely it was an automated pull. A monitor would be pretty lame now a days if it could only do those two frequency. The vertical refresh range for this monitor is 56hz-75hz depending on the resolution (pg18 of the manual)