It’s best to upload the image you’re referring to so I can count and locate the horse faces for you!
With well-known optical illusions and puzzle images found online, the exact number depends on the specific image:
The famous oil painting (“Pikes and Ikes” / Bev Doolittle): In this snowy, rocky landscape, you usually see 5 horses (including bodies/heads) at first glance. If you look more closely, you can often spot up to 7 horse heads or silhouettes hidden within the rocks and snow.
Other drawings / “find-the-hidden-object” puzzles: Depending on the specific puzzle, the number often varies between 4, 5, 7, or even more than 10 hidden faces.
If you show me the image or describe it in more detail (e.g., drawing, photo, rocks in the background), I can tell you exactly where they are hiding!