Yes freesync is for amd cards it will not work with nvdida cards, the monitor itself will work fine you just wont be able to use freesync with an nvidia card. If you want a monitor with variable refresh rate tech then you should look at g sync monitors.
What they basically do is match the framerate your system is putting out to the monitors refresh rate. So for example if your game was running at 85fps the monitor will be running at 85hz, if your game is running at 40fps the monitor is running at 40hz, etc. This eliminates screen tearing when inside the gsync and freesync range, it also feels much smoother when the framerate is moving around all over the place than it would feel when using vsync.