the.com/voiceover

means A voice track recorded separately and laid over footage or performance, narrating, explaining, or supplying dialogue the viewer never sees spoken aloud.

from A 20th-century compound from film and broadcasting jargon, literally 'voice' placed 'over' the visual or musical track. It emerged alongside radio and cinema sound technology, as studios needed a term for narration added in post-production rather than spoken on camera — the word just describes the physical act of laying audio over picture.