WordPress custom metabox for custom post type

custom-metabox.php

/**
 * Contact meta boxex
 * Custom post type name is "prefix-contact"
 */
function prefix_contact_add_meta_box()
{
   add_meta_box( 'contact_email', 'User Email', 'prefix_contact_email_callback', 'prefix-contact', 'side', 'low');
   
}

/**
 * Generate Html For the cutom Metabox
 * @param $post
*/
function prefix_contact_email_callback($post)
{
    wp_nonce_field( 'prefix_save_conatact_email_data', 'prefix_contact_email_meta_box_nonce');

    $value = get_post_meta( $post->ID, '_contact_email_value_key', true );

    echo '<label for="prefix_contact_email_field"> User Email Address</lable>';
    echo '<input type="email" id="prefix_contact_email_field" name="prefix_contact_email_field" value="'. esc_attr( $value )  .'" size="25">';
}
/**
 * Validate & Save data for the custom metabox
 * @param $post_id
 */
add_action( 'save_post', 'prefix_save_conatact_email_data');
function prefix_save_conatact_email_data($post_id)
{
    //Validate if the wordpress nonce is exsit
    if(!isset($_POST['prefix_contact_email_meta_box_nonce']))
    {
        return;
    }

    // Varify WordPress nonce
    if(!wp_verify_nonce( $_POST['prefix_contact_email_meta_box_nonce'], 'prefix_save_conatact_email_data' ))
    {
        return;
    }

    // Skip Auto save
    if(defined('DOING_AUTOSAVE') && DOING_AUTOSAVE)
    {
        return;
    }

    // Validate if the curent user can edit the post
    if(!current_user_can( 'edit_post', $post_id ))
    {
        return;
    }

    // Validate if the filed is not empty
    if(!isset($_POST['prefix_contact_email_field'])){
        return;
    }

    $email_data = sanitize_text_field($_POST['prefix_contact_email_field']); //Sanitize the filed

    update_post_meta( $post_id, '_contact_email_value_key', $email_data);
}