Horses have some of the largest eyes of any land mammal with a diameter of about 2 inches. Like many prey species, horses eyes are located on the side of their head so they have a wide range of vision. They can see nearly 360 degrees, and have blind spots only immediately in front and immediately behind their bodies.
Horses mostly use 𝙢𝙤𝙣𝙤𝙘𝙪𝙡𝙖𝙧 𝙫𝙞𝙨𝙞𝙤𝙣, meaning both eyes are used separately. So a horse can see and process different things happening on different sides of their body. However, a horse also uses 𝙗𝙞𝙣𝙤𝙘𝙪𝙡𝙖𝙧 𝙫𝙞𝙨𝙞𝙤𝙣 when looking ahead, so they can focus both eyes on a single object in front of them. They can't use monocular vision and binocular vision at the same time, but rather switches the type of vision they are using by changing the position of their head to face the object.