The refresh rate of a display is the number of times per second that the image refreshes on the screen. For example, a 60Hz display will update the screen 60 times per second.
Overall, the refresh rate determines how smoothly motion appears on your screen. For Video Playback, 60 Hz is recommended over 30 Hz. The playback quality is noticeably better.
To Change the Refresh Rate:
If you are utilizing 4K displays, take a look at the HDMI cables being used. Catapult recommends utilizing an HDMI 2.0 or HDMI 2.1 cables if you are utilizing 4k resolutions. This article on HDMI Cable Types covers the different specs and supported resolutions on the different HDMI cable types.