Read this article – https://developer.wordpress.org/themes/advanced-topics/child-themes/#using-functions-php
Just add the next code in functions.php of your child theme:
if ( ! function_exists( 'etheme_get_mini_cart_empty' ) ) {
function etheme_get_mini_cart_empty(){
?>
<div class="woocommerce-mini-cart__empty-message empty">
<p><?php esc_html_e( 'No products in the cart.', 'xstore' ); ?></p>
<?php if ( wc_get_page_id( 'shop' ) > 0 ) : ?>
<a class="btn" href="https://www.cuentosenlacabeza.com/nuestra-libreria/"><span><?php esc_html_e('Return To Shop', 'xstore') ?></span></a>
<?php endif; ?>
</div>
<?php
}
}
Regards