apply_filters and add_filter example.php

<?php
/** This code can be placed in functions.php file of Child theme or any other plugin */


add_filter( 'rbr/admin/settings/advance/fields', 'adding_color_field_to_advance_section' );


function adding_color_field_to_advance_section( $fields_array ) {

	// Modify this fields array
	$fields_array[] = array(
		'id'    => 'advance_color_field',
		'label' => 'Advance Color Field',
		'type'  => 'color'
	);


	return $fields_array;
}


add_filter( 'rbr/cpt/register/book/args', function($args_array){

	$args_array['menu_icon'] = 'dashicons-carrot';

	return $args_array;
} );