Telecommunications companies need to put their equipment (like antennas and towers) somewhere in order to provide cell phone and internet service to people. They can't just put it anywhere they want, though - they need to ask the owner of the land for permission to use it.
Sometimes, the owner of the land agrees to let the telecommunications company use it for a while in exchange for money. This is called a telecommunications lease.
Think of it like renting a toy from your friend - your friend lets you play with their toy for a while in exchange for some of your allowance money. The telecommunications company is renting the land to put their equipment on instead of a toy, and they're paying the landowner (like your friend) some money for the privilege.
The lease usually lasts for a set amount of time, like five or ten years. After the lease is up, the telecommunications company might renew it or they might move their equipment somewhere else.
The money the landowner gets from the lease can be helpful for paying bills, like your allowance money can help you buy something you really want. The telecommunications company gets to use the land to provide service, and you get to use your friend's toy for a little while. It's a win-win for everyone involved!