Translation:I am doing well, because I have a duck.
It is certainly possible and even common to say, "I'm good", but it is actually grammatically incorrect. I am in agreement with Atalina; good is an adjective. So, if I say, "I'm good", what I am saying is that I am morally upright and beneficent. Well is an adverb and describes HOW I am doing. Farti can be (more accurately) translated "to fare". So, mi fartas bone can be most succinctly translated as "I fare well". "Good" would not work there. (I realize no one would actually use the verb "fare", but this helps me.)