confirm_user_signup( string $user_name, string $user_email )

function confirm_user_signup($user_name, $user_email) {
	?>
	<h2><?php /* translators: %s: username */
	printf( __( '%s is your new username' ), $user_name) ?></h2>
	<p><?php _e( 'But, before you can start using your new username, <strong>you must activate it</strong>.' ) ?></p>
	<p><?php /* translators: %s: email address */
	printf( __( 'Check your inbox at %s and click the link given.' ), '<strong>' . $user_email . '</strong>' ); ?></p>
	<p><?php _e( 'If you do not activate your username within two days, you will have to sign up again.' ); ?></p>
	<?php
	/** This action is documented in wp-signup.php */
	do_action( 'signup_finished' );
}