Anemoculi are a type of Oculi in Genshin Impact. These significant resources can be used to rank up Statues of the Seven, giving you some pretty big stat boosts and benefits.
The Anemocule will appear in the world as small blue objects floating in the air. Some of them will be quite close to the ground and you just need to jump to grab them. Others may involve climbing or setting up wind tunnels that will lift you into the air to get them.
The map above will show you exactly where they all are, using Genshin Impact's Interactive Map.
When you're near them, they'll be marked on the minimap with a small star icon, so they're very hard to miss once you know their general location. They can involve a bit of work, especially as you get deeper into the game.
While it's certainly not essential to find them all to get a powerful party, the rank up benefits of the Statues of Seven are definitely worth it, as it's one of the ways to increase your stamina. It's also worth noting that you'll only find Anemoculus in the Mondstadt region of the game, and they can be used to rank up Statues of the Seven that are in the same region.
In Liyue, you will find similar items called Geoculus, and these are used to rank with the statues in that region.