pmpro-signup-shortcode-gettext-example.php

<?php
/**
 * Translate or change a text string in the PMPro Signup Shortcode.
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmpro_signup_shortcode_gettext_example( $translated, $text, $domain ) {
	if ( 'pmpro-signup-shortcode' === $domain ) {
		switch ( $text ) {
			case 'E-mail Address':
				// Your custom text string or translation here.
				$translated = 'Your translation here';
				break;
		}
	}

	return $translated;
}
add_filter( 'gettext', 'my_pmpro_signup_shortcode_gettext_example', 10, 3 );