Exceptional Days option in Modern Events Calendar is for those events that occur every day of the month or their repetitive schedule require some days to be excluded.
Modern Events Calendar Exceptional Days Options
You can enable this option by going to MEC Settings > Single Event > Exceptional Days and activate the Show exceptional days option on Add/Edit events page checkbox.
Using this option you can exclude certain days from the period that your event goes on.

How does it work ?
Consider that you have a recurring event that occurs from May 10th to May 30th. But you want to remove 2 occurrences of that event. May 19th and 22th.
Hello, why does it mark me every month the same active day as today? In other words: the current day is marked every month! How can I correct this error? Thanks.
Hi there
Thank you for contacting us
Please refer to webnus.net/support to create a ticket there.
Our experts will help you with it.
Is there a way to set the exceptional days globaly for all events? For example, holidays troughout the year so that I don’t have to go into each of the events to set up Christmas break etc.
Hello,
Unfortunately not, It’s not possible.