Earlier quoted context omitted.
That's the "Chinese room" argument: https://en.wikipedia.org/wiki/Chinese_room It has been very well discussed before I don't understand how anyone sane can argue against it (and indeed you can see on Wikipedia that the replies to it are sparse and don't make any sense).
It's fairly obvious to me that the room as an entire system understands Chinese. The human in his thought experiment would just represent the small fraction of the brain that encodes/decodes symbols.
Today we know the program to do this is always going to be inscrutable to Searle. His role is no different from someone using Claude to write an email.