title: What does "A synchronized block in Java is synchronized on some object" mean..?
body: <p>I understand that to achieve thread safety and synchronization we use either synchronized block or method.<br>
  But I am not able to understand the statement-<br>
  "A synchronized block in Java is synchronized <strong>on some object</strong>"</p>
  
  <p>Any real world example will be helpful.</p>