xbacklight:tldr:b631f

The command "xbacklight -dec ${75}" is used to decrease the screen brightness using the xbacklight utility.

Here's a breakdown of the command and its components:

• "xbacklight" is a utility that is commonly used in Unix-like systems to control the backlight brightness of the display.
• "-dec" is an argument or parameter for xbacklight command, which stands for "decrease." It instructs xbacklight to decrease the brightness by a specified value.
• "${75}" is a variable or value that represents the amount of brightness decrease desired. In this case, it is set to 75, meaning the brightness will be decreased by 75 units or percentage points.

Overall, the command is requesting xbacklight to decrease the screen brightness by 75 units (percentage points). The exact effect will depend on the current brightness level and the capabilities of your display.