Can someone please explain to me what Third-Person Omniscient means in terms of point of view?
The key to understanding omniscient point of view is in the knowledge of what the word omniscient means: all-knowing. An omniscient narrator supplies more information about all the characters and events than any one character could know. The omniscient narrator knows the thoughts, feelings, and speech of all the characters. Omniscient narrators differ from other third person narrators in this universal way, and differ from other third person narrators in this respect.
The third-person limited narrator, for instance, is like the omniscient narrator in that he/she speaks in the third person (using he, she, it, and they or people's names). However, this narrator can only reveal the inner life of one character.
The third-person objective narrator simply reports as a detached observer, never disclosing anything about what any character thinks or feels.
There are two parts to this kind of narrator or point of view.
First, it is done from the third person perspective. That means that the narrator is not referring to themself as I. The narrator is not a character in the story. Instead, he or she is "watching" the characters and telling us about them. The narrator will refer to the characters in the third person. They'll say "he dove off the cliff" of something like that.
Second, the narrator is omniscient -- he knows everything. This means he can know what characters are thinking. So he can say "David mentally said good bye to his wife and children because he was sure he was going to die as he jumped off the cliff."