add_filter( 'manage_users_columns', 'prefix5487_modify_user_columns' );

function prefix5487_modify_user_columns( $column ) {
    $column['orders'] = __( 'Order count' );
    return $column;
}


add_filter( 'manage_users_custom_column', 'prefix5487_user_order_column_value', 10, 3 );

function prefix5487_user_order_column_value( $val, $column_name, $user_id ) {
    switch ($column_name) {
        case 'orders' :
            return wc_get_customer_order_count( $user_id );
        default:
    }
    return $val;
}


add_filter( 'manage_users_sortable_columns', 'prefix5487_make_registered_column_sortable' );

function prefix5487_make_registered_column_sortable( $columns ) {
    return wp_parse_args( array( 'orders' => 'orders' ), $columns );
}