What you probably looking for is Else condition.
If condition A -> action A
else -> action B
You can also use other conditions after Else:
If condition A -> action A
else if condition B -> action B
else if condition C -> action C
else -> action D
"Else" can't be used with triggered events like "On created" event on your screenshot.
Triggered events have a little green arrow and usually start with "On.."
You can see the list of all expression in the expression editor, there is a semi-transparent window with all objects in your project. If you click System for example, you'll find all system expressions.