Function: indicate-copied-region

Indicate that the region text has been copied interactively.
If the mark is visible in the selected window, blink the cursor
between point and mark if there is currently no active region

If the mark lies outside the selected window, display an
informative message containing a sample of the copied text. The
optional argument MESSAGE-LEN, if non-nil, specifies the length
of this sample text; it defaults to 40.