what is this place

It's only open at certain times. You go and fill with the water there to create a to give to one of your pets to turn them into one of the new and wonderfully drawn Glade pets ;)

Also there's an achievement for creating the potion

There's a new pet color out, the Glade color. In order to make a glade potion, you get an and go to the Glade between 8AM-9AM subeta time or 8PM-9PM subeta time and fill the pitcher.

The glade is located here: http://www.subeta.net/explore/glade.php

The pitcher restocks in Seedlings at R81 and is currently a possible prize from quests, but will soon go up in rarity. ^^