This is the 807th most frequent Japanese word.
うえ
"Above," "up," or "over."
In this sentence, 'うえ' indicates a positional relationship, meaning 'on' or 'above'.
机の上に本があります。
There is a book on the desk.
Here, 'うえ' metaphorically represents an abstract addition or burden.
大人のうえに色々な責任があることを理解しています。
I understand that adults have various responsibilities on them.
In this example, 'うえで' functions as part of an expression meaning 'in the context of' or 'as part of'.