The first thing writers invariably talk about when discussing omniscient viewpoint (OPOV) is “multiple viewpoints.” They see it dipping into this character’s head and that character’s head and apply what they know already from Third Person or First Person. Then they usually identify it as head hopping, because their frame of reference is Third Person where they’ve been told not to head hop.
It can look confusing from this perspective.
Especially since OPOV doesn’t see the world through any character’s eyes. It’s a single narrator who tells us what the character is thinking and experiencing, and at the same time, can see things the character can’t. Writing is taught to go from the parts to the whole, and most of the viewpoints follow this same direction. The viewpoint character — and reader — only know what’s happening in the story at this point, and discovers things as they happen. On the other hand, OPOV goes from the whole to the parts — the reverse of how things are normally done. The narrator knows everything that’s going on and may slip in things that the characters won’t know.
When you’re trying to learn about OPOV, start with thinking about the story being told by a single outside narrator, not the characters.