The keyboard combination "CTRL W" or "CTRL+W" means pushing both the CTRL key and the W key at the same time. Its function depends on the program, operating system and localization used. However, there are some basic functions that are commonly achieved by this combination.
For Microsoft Windows programs such as Excel, pushing CTRL and W simultaneously closes the focused window. This means that whatever window the user is operating is closed. Hitting ALT and F4, CTRL and F4, or ALT and the space bar then C also performs this function as well. However, in UNIX, pushing CTRL and W deletes the last word typed.