This is a title.
I suppose this should say that something is good. But how can this make sense grammatically? Is not "Qu'est-ce que" always used for questions?
Qu'est-ce que is here to say that the thing is very good, it is an exclamation here, and not a question.
"Qu'est-ce qu'elle est belle" means "She's really gorgeous". "Belle" is "pretty" in French, and "Qu'est-ce qu'…" helps accentuate her beauty.
Is not "Qu'est-ce que" always used for questions?
I think it is similar to the usage of what in What a beauty!
And you can think of the sentence you posted as meaning
What a goody!
As Laure pointed out:
The usage of "Qu'est-ce que" in this sentence is more akin to how than to what. So to clarify:
Qu'est-ce qu'elle est belle! --> How beautiful (she is)!
But in the case of your specific example:
Qu'est-ce que c'est bon! --> How good/delicious/tasty (it is)!
is common french but not so common english.