Hi,
Prognosis is really difficult to judge because it depends so much on individual factors (age, other illnesses etc.) and just plain luck.
If I understand correctly, your dad will have undergone CT and bone scans that have ruled out spread to bones and organs (e.g. liver, kidneys, etc.). I'd expect that he will be prescribed hormone therapy (androgen deprivation therapy or ADT) for longer than 28 days (e.g. 3 years) and probably to be prescribed other hormone therapy as well (e.g. Abiraterone, Enzalutamide, daralutamide or apalutamide). These would be things to discuss with the Nurse or at the next oncology appointment.
Some of the best evidence on prognosis comes from the Stampede trial. I think this might be the most relevant for your dad:
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)02437-5/fulltext
It found that the majority of men were alive at 9 years after starting therapy.
It's all a bit overwhelming at first. But hopefully it will become clearer. Keep on supporting your dad at the meetings. You can always ask for a different consultant if the one you have isn't communicating clearly.