could it be translated by : "it's good that you have a pet" ?
No, this would be Είναι καλό που έχεις ένα κατοικίδιο or Είναι καλό ότι έχεις ένα κατοικίδιο :)
Does the "verb" after να changes depending on the person? I understand why Tomvince asked that and your answer but...
Since we are learning about "Gerunds", a better translation (I believe) would be: "It is good having a pet". I used this and DL said it was "Correct".
Ok, I have read all the comments and am a native English speaker. I, too, wondered about the 'έχεις' and entered 'It is good that you have a pet' (Tomvince!) which was accepted. :)