I have come across a definition of compound prepositions on
"Compound prepositions are those prepositions which are formed by prefixing the preposition to a noun, an adjective or an adverb" Examples: above, along, inside, around, before, behind, below, beneath etc.
The boys ran around the bench
The book is inside the cupboard
The fan is above the table
I am unable to understand this definition, members are requested to make this clear to me.
Thanks in advance!