On the Events >> Shortcodes page, there is an "excerpt" argument along with a "character" limit option: [eab_calendar show_excerpt="yes" excerpt_length="50"]
* I cannot create an excerpt at all when creating an event. There is no excerpt field.
* There is no option to add "excerpt" to the admin screen from "Screen Options".
So either the instructions are wrong, or the excerpt field is broken.
I have tested this on my main site, and on a vanilla site with no plugins.