What do you mean by "leaked base"?

Question

Information Security

Taking on the writing of the backend, each time I deal with the issue of hashing passwords - standard measures. And although it is approximately clear to me for what scenarios this is done, it is not clear to me how this can help protect data from unauthorized changes. If an intruder gets enough access to "steal" it from the server, then can't he change the data as he sees fit directly? What is the emphasis on, that the cracker will get confused in the business logic? Or is it somehow limited in actions by the server configuration (if so, why does it allow it to read the database)? Or does he not have access to the database itself, only the ability to get its dump? In general, if you have experience, please describe briefly the possible hacking process and how hashing helps in this case - I will be grateful. Google didn't turn up anything useful.