Answer : The oxidized element is, hydrogen.
Explanation :
Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.
Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.
Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.
The balanced redox reaction is :

The half oxidation-reduction reactions are:
Oxidation reaction :

Reduction reaction :

In this reaction, the oxidation state of 'H' changes from (0) to (+1) that means 'H' lost 1 electron and it shows oxidation reaction and the oxidation state of 'Cu' changes from (+2) to (0) that means 'Cu' gain 1 electron and it shows reduction reaction.
Thus, 'H' is oxidized and 'Cu' is reduced.