how to display $page array? How to display the entire $page array like shown below? 
I have devel module installed and have tried "dsm($page)" but that just shows the word "Array".
You can try dsm($page) in page.tpl.php of your theme to see the contents of $page array.

As mentioned by Clive, context really matters. If you will try to print $page array when it has no elements then it will display word Array.