We've created Sprints several sprints for the months going forward but how do we tell Agile Manager which days are Holidays and therefore shouldn't be counted in the Sprint?
Since almost everyone is going to be out for the holidays, then by all means simply make your sprint shortern and adapt sprint dates accordingly.
Another idea is to adjust the capacity of the members according to the holidays.
Just go to "Teams", open the team members and set the value at "Work hours per day".
Hope it helps :)