Who is Dioscuri: Castor and Polydeuces (from Electra) from Euripides V and what is their importance?

The Dioscuri are Zeus' and Clytemnestra's brothers. They have ascended as gods. At the end of the play, the Dioscuri come to tell Electra and Orestes their fates, and although they have successfully avenged their father's murder, they also must be punished for killing their mother. The Dioscuri decree that Electra must marry a foreigner and be exiled to another land. Orestes is sent to Athens where he is tried and narrowly acquitted of matricide.