How to add PHP code in functions.php wordpress

<?php //Insert ads after second paragraph of single post content. add_filter( 'the_content', 'prefix_insert_post_ads' ); function prefix_insert_post_ads( $content ) { $ad_code = '<div>Ads code goes here</div>'; if ( is_single() && ! is_admin() ) { return prefix_insert_after_paragraph( $ad_code, 2, $content ); } return $content; } Hi, how to repace <?php $a1 = get_field('fa1', 'option'); if ($a1) : … Read more