MyTravel - Change Add to Cart text as Book

functions.php

add_filter( 'woocommerce_product_single_add_to_cart_text', 'mas_travels_custom_single_add_to_cart_text' );

 function mas_travels_custom_single_add_to_cart_text( $text ) {
    $text = esc_html__( 'Book', 'mytravel' );

    return $text;
}