Only admin can add holiday.
Other users can view holidays applicable for there location.
Adding Holidays
Fields: Name, Start Date, End Date, Business Location, Note
Permission & Settings for management for HRM
Approve Leave:
By default only admin can approve leave added by other users. But you can assign the Approve leave permission to any other role & assign it to a user. User having approve leave will be able to approve leaves added by other users.
Allow users to enter their own attendance:
You will find this option in HRM -> Settings -> HRM tab. If enabled other users will be able to enter their own attendance and vice-versa.