Complex sentence: NRs (national representatives) from all the ESN member countries together form the Council of National Representatives (CNR) that during the year represents the voice of the AGM and after the AGM is the highest decision making body of ESN.
Split into simpler sentences: NRs (national representatives) from all the ESN member countries together form the Council of National Representatives (CNR). During the year they represent the voice of the AGM and after the AGM it is the highest decision making body of ESN.