captcha-module/Application/translations/en/oecaptcha_en_lang.php

<?php
/**
 * @category      module
 *
 * @author        OXID eSales AG
 *
 * @see          http://www.oxid-esales.com/
 *
 * @copyright (C) OXID eSales AG 2003-20162016
 */
$sLangName = 'English';

$aLang = [
    'charset'                         => 'UTF-8',
    'MESSAGE_WRONG_VERIFICATION_CODE' => 'The verification code you entered is not correct. Please try again.',
];