Elements is a Prolog list of JPL representations of the array's elements (values or references, as appropriate). This is a utility predicate, defined thus:
jpl_array_to_list(A, Es) :- jpl_array_to_length(A, Len), ( Len > 0 -> LoBound is 0, HiBound is Len-1, jpl_get(A, LoBound-HiBound, Es) ; Es = [] ).