gettext-pmpro-profile-checkout-pages.php

<?php
/**
 * Change the gettext strings on the PMPro member profile edit and checkout pages.
 *
 * 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 gettext_pmpro_profile_checkout_pages( $translated_text, $text, $domain ) {
	global $pmpro_pages;
	if ( ! empty( $pmpro_pages ) && ( is_page( $pmpro_pages['checkout'] ) || is_page( $pmpro_pages['member_profile_edit'] ) ) && 'paid-memberships-pro' === $domain ) {
		switch ( $text ) {
			case 'Email':
				$translated_text = 'Business Email';
				break;
			case 'Email Address':
				$translated_text = 'Business Email';
				break;
			case 'Confirm Email Address':
				$translated_text = 'Confirm Business Email';
				break;
		}
	}
	return $translated_text;
}
add_filter( 'gettext', 'gettext_pmpro_profile_checkout_pages', 20, 3 );