understand threades in java code example

Example: create thread java

class RunnableObject implements Runnable {
   private Thread t;
   private String threadName;
   
   RunnableObject( String name) {
      System.out.println("Creating " +  threadName );
      threadName = name;
      t = new Thread (this, threadName);
   }
   
   public void run() {
      System.out.println("Running " +  threadName );
   }
   
   public void start () {
      System.out.println("Starting " +  threadName );
      t.start ();
   }
}

public class TestThread {

   public static void main(String args[]) {
      RunnableObject R1 = new RunnableObject( "Thread-1");
      R1.start();
   }   
}