Changing the configuration of your computer is a two steps process. You must first enter the parameters of the new configuration and then perform whatever is needed to make those configurations effective. On many operating systems, this is generally carried by a reboot.
Linuxconf lets you probe your computer and compare step by step the current configuration (how your computer is performing now) and the intend configuration. This implies for example, the following operations:
The Activate configuration menu produces a small report showing exactly what has to be done to make operationnal the new configuration. At this point you will be allowed to either let Linuxconf do the change or do nothing.
If you decide against activating the configuration, all is not lost. You can select this menu again and Linuxconf will report the same results, even if you have quit Linuxconf in the mean time.
Each time you quit Linuxconf, it triggers the same process as this menu item and let you accept the changes (make the new configuration operationnal) or not.
This "activate configuration" menu will probably seldom be used with the interactive mode of Linuxconf. It is essential with the html mode where there is no such a thing as quitting Linuxconf: Each html page is in itself a small Linuxconf's session.