- 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 your character is stealthed. It does not check whether an enemy can detect you.
Why you might use it
Tells whether you are stealthed, so stealth openers come first: Ambush, Garrote or Cheap Shot for a Rogue, Ravage or Pounce for a Druid in Prowl. It is also a good switch condition between an opener rotation and the normal one. It does not tell you whether an enemy can see you. See also Shapeshift Form.
Example
you are stealthed
Settings
What each setting in the condition editor means, from the game's own help.
Matches while the game reports your character as stealthed. It does not test whether an enemy can detect you.