when I use command-shift-M, Terminal appears with the command to send my desktop somewhere

For some reason Mojave's Applications -> Utilities -> Terminal has installed a service "Open man page in Terminal" which is Command-Shift-M. It seems to take the contents of the clipboard or selected text. So what gets displayed is going to be a function of what you have currently selected, or in your clipboard.

It does not make itself active for all apps. For example, it is not in the Service menu for TextEdit or Finder. But I found it in Firefox.

You should be able to disable it via the System Preferences -> Keyboard -> Shortcuts tab, of if you like it (uncheck the box [_], you can give it a different hotkey combination.

To confirm my understanding here, this is a question about Microsoft Office and its customizations, and specifically about Word?

What is shown here is the output of a command line command within Terminal.app, and the first entry is a component of macOS.

Your desktop is not being sent anywhere.

The command line command issued here looks to be “man -k remote” or “apropos remote”. Either directly, or that’s what happens when Terminal.app is issued on your Mac. (That latter behavior would point to a problem in a login-related procedure. Does that same output and same exit happen when you launch Terminal.app?)

Apple Remote Desktop is not involved here.

Which version of macOS? There’ve been recent patches available for both High Sierra and Mojave.

Which version of Office? Office 2016, 2019, and 365 are the only supported versions, and earlier Office versions are known to have some problems on newer macOS releases.

According to one list of Word shortcuts, Command Shift M is a paragraph indent yank.

https://shortcutkeys.info/macos-microsoft-word-shortcut-keys/

There are two likely possibilities here. One is a system-side customization in macOS for that shortcut, and the other is a customization somewhere within Word.

Not entirely certain what you mean by “launch a micro”, and will assume that you’re invoking a Word macro with that shortcut.

https://support.office.com/en-us/article/Create-or-run-a-macro-C6B99036-905C-49A6-818A-DFB98B7C3C9C

I’d check with the folks over in the Microsoft forums, and see if they can assist with invoking macros and with troubleshooting this, and I’d ensure you’re on at least Office 2016, Office 2019, or Office 365. This doesn’t look related to Apple Remote Desktop, amd there’s not much Microsoft Office traffic around here, and I definitely don’t know much about Office...