I am using wordpress with woocommerce and I am trying to manipulate a copy of myaccount.php The default code uses some variables of some sort that I am not familiar with nor have I been able to find documentation on. The variables in question are %1$s, %2$s and %s

<p class="myaccount_user">
<?php
printf(
    __( 'Hello <strong>%1$s</strong> (not %1$s? <a href="%2$s">Sign out</a>).', 'woocommerce' ) . ' ',
    $current_user->display_name,
    wp_logout_url( get_permalink( wc_get_page_id( 'myaccount' ) ) )
);
?>

<?php
printf( __( 'From this page you can view your recent orders, manage your shipping and billing addresses and <a href="%s">edit your password and account details</a>.', 'woocommerce' ),
    wc_customer_edit_account_url()
);
?>
</p>

How can I identify the variables, what they represent and how to use them?

Thank you.