If both your monitor is 120Hz or higher, and your computer is able to push 120fps or more in a particular game, then you should see 120 frames getting displayed every second.
But if your monitor is only 60Hz, it will only update the image it is displaying up to 60 times per second, even if your computer is able to pushing out significantly higher frame rates than that.
And similarly, if your monitor has a high refresh rate like 120Hz or above, but your computer isn't powerful enough to render that many frames per second in a particular game, you will only see as many frames as your computer can render.
Another thing to consider is that many televisions will advertise having a high refresh rate, like 120Hz or 240Hz, but they don't actually take more than 60Hz video input, and just use interpolation or backlight strobing to justify advertising a higher number, even if that number isn't particularly beneficial to gaming. Computer monitors, by comparison, almost always advertise the actual refresh rate that they can take as input and display.
A 120Hz refresh rate doesn't tend to be all that common on computer monitors though, with most of today's high-refresh screens typically offering 144Hz or more, while standard-refresh screens offer just 60-75Hz. You might find some that output 100Hz or 120Hz though.
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thanks for the answer, but I still don't understand every frame is "new" or is it like a "new" frame and will the successor of that "new" frame be the same?