In case you aren’t familiar with Zelda the way some die-hard nerds on the internet (that includes me, for the most part), there is a timeline in which the various games are placed. The many adventures of the spritely, green-clad Link and his little pony, the aloof and mysterious princess, and the evil, thieving Ganon/dorf (as explained in the series first chronologic installment of Skyward Sword, on Wii) are bound together in a sort of reincarnation-style Groundhog Day (the movie, featuring Bill Murray).
That’s right, every new game that comes out is a new episode in the saga, and each takes place at a specific time in the history of the fictional land of Hyrule. So, for those who keep track of that sort of thing, speculation has been high regarding Breath of the Wild and where on the timeline it falls. The producers have previously confirmed that the game takes place after Ocarina of Time, which is somewhere in the middle, but the image above suggests a more narrowed window.
The creatures above are called Koroks. They are the children of the Great Deku Tree, and the first and only time they have appeared in a Zelda game was The Wind Waker, where the entire world was flooded and Hyrule was submerged below the waves. What’s also interesting is that the Koroks are said to be the descendants of the Kokiri people, the forest-dwelling clan to which Link’s incarnation belonged at the beginning of Ocarina of Time. Their inclusion in this game should indicate that this game takes place either right before or right after Wind Waker, though I do believe there is some line in WW that stipulates a hero hadn’t existed for quite some time prior to the events of that game.
If you’re lost after reading that, don’t worry. You don’t need to know any of that to enjoy BotW when it comes out in a few weeks. Things like the Koroks and the inevitable other nods they’ve included are just meant to serve as Easter Eggs.