- Not available on that edition (the reason is in the tooltip)
- Depends on the setting, your class or another addon (details in the tooltip)
What it does
Checks if the name of the zone you are in, or the subzone when SubZone is ticked, exactly matches the name you enter.
Why you might use it
Checks the zone (or, optionally, the subzone) you are in by name, so you can switch to a rotation tuned for a particular raid or dungeon, such as Blackwing Lair, or for a specific area of a zone. Zone names are the ones the game shows, in your client's language. See also Instance and Zone PVP.
Example
in Blackwing Lair
Settings
What each setting in the condition editor means, from the game's own help.
SubZone - Use the SubZone text instead of Zone text (eg. Valley of Strength instead of Orgrimmar)
Zone - The zone you are in.