"I am doing well, because I have a duck."
Translation:Mi bone fartas, ĉar mi havas anason.
Programmer here; this is a sentence i have used before: https://i.pinimg.com/736x/30/54/5e/30545efd6fed2f16fb6355c53c9623a9--funny-jokes-funny-gifs.jpg
The -n suffix means that the noun is a direct object. In other words, if the noun is directly receiving the action (in this case the duck is being 'had'), it has to have an -n ending. Also keep in mind that prepositional objects do not get the -n ending. So "en [noun]", "al [noun]" etc. get no -n.