What is the meaning of this sentence?
What is the meaning of für das in the sentence "Zweitens birgt das Thema dieser Präsidentschaft großes Potenzial für das, was jetzt notwendig ist,"?
'was jetzt notwendig ist' is a relative clause. 'das' is the antecedent (the thing the relative clause expands on.) A literal translation would be '...for that which is necessary now.' Or less formally '...for what is necessary now.'
Because 'das' is not playing the same role as it would in 'dafür'. 'dafür' is an adverb meaning 'for that' where 'that' points back to something. 'Er wurde dafür verhaftet.' 'He was arrested for that.' 'that' being something we've already heard about. In your sentence 'das' is not pointing to something. Rather it is the thing being pointed at by the relative clause. That's the only reason it's needed, to give the relative clause something to point at.