When the Search Commands feature is activated, a head-up display (HUD) is shown and can be used to quickly search commands by their names. As the search string is typed, all matching commands are shown in a list below the search field.
To execute a command:
Use the mouse to click on one of the items shown in the list. This will immediately run the selected command.
Use the arrow keys in the keyboard to navigate through the items shown in the list and press Enter to run the desired command.
This feature is available in Writer, Calc, Impress and Draw.