You can toggle the touchpad off and on with that button.
TouchPad Button: Some laptops have a button near the top of the touchpad that allows you to quickly enable and disable the touchpad. How to enable the touchpad in Windows 7 and earlier.How to enable the touchpad in Windows 8 and 10.How to disable the touchpad in Windows 7 and earlier.How to disable the touchpad in Windows 8 and 10.The exact steps may differ slightly, depending on the laptop’s manufacturer, so you may need to use some intuition to achieve your desired outcome.
Most users find themselves in situations where they would like the touchpad on (e.g., no external mouse) or off (e.g., accidentally moving the mouse cursor with their palm while typing). The touchpad on a laptop is a convenient way to add the functionality of a mouse without needing an extra peripheral.
