General Zaroff, from his well-provisioned castle on "Ship-Trap Island", is in the practice of capturing sailors and hunting them, one at a time, across the expanse of the island, in an effort to give himself purpose. Rainsford, another hunter, is stranded on the island, and Zaroff gives him a great deal of exposition and explanation because he perceives him as a peer, at least initially.
Rainsford is, as we might expect, shocked and disgusted by Zaroff's business. Zaroff justifies himself by arguing that he only hunts the "scum of the earth", and that he acquires them not by any real direct capture or intervention, but largely because the island is well-named: he states that an "angry god of the seas" will sometimes send a ship to him (by smashing it into the rocks that surround the island). However, when this doesn't happen, he will "help Providence a bit". Providence refers to the "will of God" or natural fate.
Zaroff has outfitted lights on a series of rocks off the coast of the island, lights which would normally, in maritime communication, signal that they mark a clear passage. In fact, they are meant to draw ships directly into the rocks, destroying them and shipwrecking their crews for Zaroff to collect.