Sometimes it is handy to be able to export your figures out of the manuscript as separate files (for instance when submitting your work to a journal for review). Manuscripts provides a number of ways to accomplish this:
A. Right click the image inside a figure panel to reveal a context menu, then click "Copy". Then paste into an app of your choice.
B. Select in the outline the figure elements or the sections that contain them, then go to File > Export and choose exporting the selection (a checkbox is shown for it in the export dialog), and choose either HTML, Markdown or LaTeX as the export format. Once exported, the folder containing the document will contain a snippet of text in the format of your choice, as well as figures exported as separate files.
C. Select the figure in the outline and drag it out of Manuscripts into Finder. You'll get a folder containing the file in the markup format you've selected in Preferences > Editing > Default markup format (Markdown by default).
The options B and C above are both special cases of being able to export a selection.