"Viewing modes" refers to the different ways in which something can be observed or seen, often referring to the options provided by a device or software to change the display settings for better viewing. Full definition
When folding back, the front cover holds your device in landscape viewing mode. (gadgetsin.com)
The interface comes with customization options, auto - scrolling, page turning animations, and various view modes for your comfort. (androidauthority.com)
Additionally, if you need to hop into different viewing modes because the screen is too bright for your drive, you can switch to the night mode view from this menu screen. (pcworld.com)