[Haskell-beginners] A tree code

Hello. There is a code below and I couldn't understand it myself. Could you help me with that please?  I especially have no idea about "data Tree alpha = Empty | Node " part. data Tree alpha = Empty | Node ( alpha ,Tree alpha , Tree alpha ) x = Node (1,Node (2,Empty ,Empty),Node(3,Empty ,Empty)) y = Node(3,Empty ,Empty) Thanks in advance