They are printing a "string representation" of the object. This representation is really calling the object's internal toString() method. Ideally you should override this toString() method as best practice to something more meaningful and human understandable.
The Javadoc for the class java.lang.Object toString() method states:
public String toString()
Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.
The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of: