Own a land title, in other words, own a government enforced monopoly privilege to land. Charge people an entrance fee to access the opportunities provided by nature and society at that location. Get money for providing nothing in return. Unless, of course, you consider allowing people to use what nature provided for free (land) in exchange for economic rent "providing something in return". The more opportunity the land you own land title(s) to gives access to, the higher the land value. In other words, the more opportunity you deprive society of, the more economic rent you can collect.
How do private land owners "get money for providing nothing in return?" A bare patch of dirt, with some grass on it, adds nothing to human society. Land only becomes valuable once a human being comes around and does something with it.
Imagine a bare piece of land, that nobody has lived on for years. A farmer decides to settle this patch of land. He harvests some crops, builds a home, and soon enough his crops grow.
Before the farmer harvested his crops, the land was useless. But now, through his hard work, the land suddenly is attractive for human settlement. The carrots he grows on that land do not rightfully belong to everyone. They do not belong to "the land," or "the people." They belong to him. Because without his hard work, the land was useless. If he sells his carrots, he is not "getting money for nothing provided in return." He is cashing in on his own effort.