Each website has its own style of displaying technical specifications, so it's hard for me to pinpoint exactly what you are talking about. However, from my experience, there are three values that can appear in brackets after the resolution:
- Aspect ratio: the ratio between the width and the height of the image being displayed. Example: 4:3, 16:9, 16:10.
- Refresh rate: the number of frames per second being displayed by the monitor. Example: 58Hz, 60Hz, 70Hz.
- The size of the monitor in inches. 4K monitors are usually between 21.5" and 31.5".
If you were talking about something, please clarify by posting the link or the complete details of the product.