Share your screen in FaceTime on Mac
With macOS 12 or later, you can share your screen during FaceTime video calls. You can look through a photo album together, view a web page at the same time or get feedback on something you’re working on, all while seeing and hearing everyone’s reactions.
While on a FaceTime call on your Mac, open an app you want to share in the call.
Click the Video button
in the menu bar, then click the Screen Share button 
.Do one of the following:
Share a window: Choose Window, move the pointer to the window you want to share, then click Share This Window.
Tip: You can also click and hold the maximise button
in an app to share the app or window.Share all windows from an app: Choose App, move the pointer to the window you want to share, then click Share All [App] Windows.
Share multiple windows: While sharing one or more windows on a Mac with Apple silicon, click Add Window. To stop sharing a window, click the minus button
on the left of the window preview.Share the whole screen: Choose Screen, move the pointer to any part of the screen, then click Share This Screen.
Change which window you’re sharing: Hold the pointer over the shared window preview, click Change Shared Window, move the pointer to the window you want to share, then click Share This Window.
Tip: To stop sharing, click the Screen Sharing icon 
in the menu bar, then click the Stop Sharing button.