Creating php pages in wordpress and assigning them to wordpress pages

MahdiY just explain that you can use PHP in your template like that

<?php
/*
Template Name: news
*/

get_header();
?>

    <div id="primary" class="content-area">
        <div id="content" class="site-content" role="main">

            <?php
                echo "This is PHP";
            ?>

        </div><!-- #content -->
    </div><!-- #primary -->

<?php get_footer(); ?>