Beneath means ‘at a lower level than’.
Beneath is most common in formal writing. We don’t use it often in informal speaking. In speaking, under and below are much more common.
Beneath as a preposition
We use beneath most commonly to describe the position of things which are at a lower level than something else:
Archaeologists discovered a gold cup just beneath the surface at the site of a Roman villa.
The metro station is right beneath the airport.
Beneath is particularly common when talking about the ground or surface directly under one’s feet:
She could feel the train coming because the ground beneath her feet was moving.
Beneath as an adverb
Beneath as an adverb isn’t very common and we mostly use it in formal writing:
She looked down from the balcony at the two men talking beneath.
In the kitchen there was a modern sink with cupboards and drawers beneath.