Geodrops are a way to leave COIN in a specific location, and many people include messages for other players to read when they have picked it up.
At first, it may seem strange to drop your COIN for someone else to have. But there's quite a few reasons why someone might do that!
For example, someone who wants to tell locals about a new coffee shop that just opened nearby could do that using Geodrops. They could also place the Geodrops in the location of the new store, which would encourage folks to walk there and pick it up.
Someone who wants to chat with nearby players or see who is using COIN in their local area might also use Geodrops to communicate.
Finally, Geodrops are used by the COIN team to issue rewards and gifts to your account — for example, "Bonus Drops" are sent via a Geodrop.