- 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 how much time is left on the cooldown of the spell you choose, for any spell rather than only your specialization's own, compared with the number of seconds you set. A spell that is ready counts as zero seconds.
Why you might use it
Compares the time left before a spell can be cast again, for any spell ID; Spell Cooldown covers your own specialization's spells. It is handy for lining things up, such as holding a big cooldown until a racial like Blood Fury is nearly ready, or saving resources when an important ability is about to come back. On Retail and WoW Forever the game hides many cooldowns during combat, and the condition is then unavailable for that spell.
Example
the cooldown on Blood Fury is less than 2 seconds
Settings
What each setting in the condition editor means, from the game's own help.
The icon next to the spell name will automatically update to display the spell that is currently selected. You can drag a new spell from your spell book or action bars into this icon slot to replace your selected spell.
Use this exact spell rank - Unticked (the default), any rank of the spell matches. Ticked, only the rank you chose matches. (only on Classic Era, TBC Anniversary, Forever)
Spell - This is a specific spell used in this condition. You may drag this spell from your spell book or action bars into the input field or spell icon to set this value. This input field has prediction enabled, so you do not have to type the full spell name, just select from the prediction frame when it appears.
Operator - How to compare Spell Cooldown with the Seconds value. This comparison uses basic mathematical comparison operations.
Seconds - The number of seconds before you can cast Spell.