From your description of what was done and what the doctor said, I do not understand it either. I suggest that you or your father have a discussion with the doctor so that he/she can explain. Any time you do not understand exactly what the point of a doctor's discussion is you need to say "stop" and ask for clarification,.
Best to you and your father
Diagnosis 2-08 Small papillary TCC; CIS
BCG; BCG maintenance
Vice-President, American Bladder Cancer Society