I got an notification when I discovered it, and I can see it on the map, but what does it do? Is it a worldwonder? What are the mechanics here?

It’s a landmark. There is a forest in real life with the same name, but it doesn’t do anything special in game, at least right now.

occasionally large swaths of forest, large mountain ranges, and some rivers (probably of a certain length) will give notifs for discovering them and get special names since in-universe they'd be very noteworthy just like natural wonders. For all I know there might be something to do with them using Nature Reserves when they get implemented, but in the closed beta Nature Reserves are inaccessible despite the tech they're on being accessible, so who knows.