Record days off and public holidays, so your day counts and Capacity report are right.
You make your own types - Vacation, Sick, Personal - and pick their colors. Importing holidays adds a Federal Holiday or State Holiday type if you do not have it yet.
Public holidays. Usually non-working days for everyone.
Leave you take. It does not lower your Capacity target; it shows as time off to make up.
Unplanned absence. Important for historical tracking.
Time off shows on Track, as markers on the Income and Hours Worked charts, and in the Capacity report as Time Off.
Holiday and PTO color tags are governed by the types defined in your Configuration panel (the gear icon in the toolbar). A new entry takes its type's color; changing a type's color recolors every entry of that type, and renaming a type renames it on every entry. An entry's own color can be changed on the entry.
Use the Year dropdown in the toolbar to switch between years; the list and the counters follow it. It offers every year that holds time off, future years included, plus the current year.