Those three weeks will have been no fun at all, a load of medics sticking pins in him etc. And add on covid so you can only see half the person's face, hospital's are not much fun at the best of times. I would say they seem to have got things done quite quickly, I suspect they have been told to start getting these services back up and running and your dad got through with no one in the queue ahead of him.
Hormone therapy is quite effective, it doesn't kill the cancer, but it sort of puts it to sleep for a while, so it will still be in his bones and liver but not growing and getting worse. Sadly after a while the cancer wakes up, but then they can try another hormone treatment, then they can move on to chemotherapy etc.
A big thing to consider is quality of life (QoL) He has to make the best of his life from now on, things will get tougher, it may take many years, but it may be only a few. Some people on this forum who are only in their 50's have drawn a line at some of the treatments and accepted a shorter life rather than the side effects of the more aggressive treatments.
When cancer spreads it is said to have metastasised (I think I have spelt that correctly) each additional bit of cancer may be called a "met". So if you hear a medic say he has one or two mets that is less bad than if they say he has loads of mets.
Keep us informed, if you find his psa let us know. Also after he's been on the hormones a few months they will do another psa test make a note of that, it should be a big drop.