What does "remove only" mean for installed programs in Windows 7?

Every application in Windows may have upto three options in 'Programs and Features' section; ie uninstall, change or repair.

Uninstall means to remove the application from the OS.
Change means to add or remove certain features or components from the application.
Repair means to verify if the application is installed correctly and if not, fix any issues with an incorrect installation.

(Remove Only) applications can only be uninstalled. The change and repair options will not be available.

The below image is for reference showing all the three available options.

This is just a convention that used to be somewhat useful in the past. It doesn't mean anything any more.

In modern Windows versions, a program can specify several options to be displayed in the "Programs and Features" panel. The default is an uninstall option, but there can also be options for repairing and changing any individual components.

However, back in the olden days of Windows 95/98, you could manage installed programs from the "Add/Remove Programs" control panel, which only contained a single option, named 'Add/Remove'. If the uninstaller supported anything more than a simple removal, it had to ask the user itself with a dialog box. To avoid user confusion, some programs that didn't support any fancy options would state so by adding "(remove only)" to the program uninstall entry.

Some people simply got into the habit of doing this and therefore it persists to this day.