How to change number of characters to show in featured slider text box?

I would like to limit the number of characters in the text of the slider. Where can this be adjusted?
Thanks for your support.

Featured slider supports WordPress Excerpts function which means that you can set it manually as well. If you want to make it shorter just add necessary content to the Excerpt box right below Post Edit screen.

If you can’t see Excerpt function underneath the post you can enable it via Screen Options located in upper right corner in Post Edit screen.

Additionally you can set excerpt filter to trim them automatically. Additional information about it you can read here:
Featured slider Excerpt function is located in header-extensions.php located in theme folder → library → structure.