php "h" meaning code example

Example 1: name of today php

$datetime = DateTime::createFromFormat('YmdHi', '201308131830');
echo $datetime->format('D');

// or 

$date = new \DateTime();
echo $date->format("D");

Example 2: show date php by letters

check here link:   http://www.eltcalendar.com/stuff/datemysqlphp.html