It just generates an event that is written to the relays. Unless relay operators actively monitor these events and remove content then nothing happens. Some relay operators may be using these event for spam filtering etc (not sure) but I don’t think anyone is actively looking at each report. This is one of the challenges that nostr faces..
Discussion
Freedom will have instances, and sometimes bombardments of things you don't want to see, nor should anyone, but if you just allow freedom, free exchange to happen, it will solve itself.