The Shortcode is a piece of code in text format, which references a function of callback (external function), in order to produce dynamic content on pages and posts edited directly in the administrative panel.
To add the code PHP is used, just put the code like this:
<?php echo do_shortcode( '[colocar-seu-texto-shortcode]' ); ?>
Don't forget to replace “put-your-text-shortcode” with your code.