This feature, first introduced in CC 2019 (version 23.0.0), on October 15 of 2018, allows users to search shapes or groups that are similar to the currently selected one, within a customizable set of parameters one can access through Properties or Control panels.

Users can have the searched artwork to strictly match the size and the appearance of the selected object, to limit the search to a specific artboards and/or canvas. We can also exclude some copies from the results.

Changes applied to the original object while in the Global Edit mode, get transferred to all found and highlighted copies of it.

There are some limitation to it. You can read more about the way it can be utilized here: https://helpx.adobe.com/illustrator/using/global-edit.html

If you have some feedback regarding this feature, please post it here in comments, or log a separate report or request here at UserVoice.