Display smarty console window:
To display the smarty debug console use the smarty {debug} code in your template.
For example in the header.tpl file add the smarty {debug} code or to any other template file you are trying to debug.
Print smarty variables on screen:
{$var|@print_r}
References:
https://www.prestashop.com/forums/topic/315879-guide-enable-smarty-console-on-the-new-prestashop-16/
https://www.prestashop.com/forums/topic/218203-solved-how-to-view-module-smarty-variables/