Does it refer to THE dolphin or dolphins in general? Is it a common usage?
The dolphin in this instance because of the "'r" at the end of "Hoffi"
Yes any "'r" is replacing a y/yr and makes the sentence specific
Thank you. How would you say "Do you like dolphins?"
Dych chi'n hoffi dolffiniaid? or Wyt ti'n hoffi dolffiniaid?
@Ellis Vaughan Are these questions more commonly used than this example sentence?
It's not a case of which is more common, it depends on what you want to say. If there is one dolphin, you would say (perhaps to a child), "Dych chi'n hoffi'r dolffin?" But if there was more than one dolphin or you were talking about dolphins in general, you would say, "Dych chi'n hoffi dolffiniaid?"