Free

// =========================================================================
// CHANGE RELATED PRODUCTS TEXT TO YOU MAY ALSO LIKE TEXT
// =========================================================================  
function change_you_may_also_like( $translated ) {
   $translated = str_replace( 'Related products', 'You may also like...', $translated );
   return $translated;
}
add_filter( 'gettext', 'change_you_may_also_like' );

// =========================================================================
// CHANGE ON SALE TEXT
// =========================================================================
function woocommerce_custom_sale_text($text, $post, $_product){
    return '<span class="onsale">Special offer</span>';
}
add_filter('woocommerce_sale_flash', 'woocommerce_custom_sale_text', 10, 3);

// =========================================================================
// CHANGE ADDITIONAL INFORMATION TEXT
// =========================================================================
/* @return string Modified value for product's "Additional information" text. */
function wpdd_change_additional_information_heading() {
    global $product;
    if( $product->id == 2028 ){
	   return __( 'Further information', 'mytextdomain' );
    }elseif($product->id == 2027){
	   return __( 'En savoir plus', 'mytextdomain' );
    }else{
        return __( 'További információk', 'woocommerce' );
    }
}
add_filter( 'woocommerce_product_additional_information_heading', 'wpdd_change_additional_information_heading' );

// =========================================================================
// CHANGE ADD TO CART BUTTON TEXT ON SPECIFIC PAGES
// =========================================================================
function translate_add_to_cart() {
    global $product;
    if( $product->id == 2028 ){
        return __( 'Add to basket', 'woocommerce' );
    } elseif($product->id == 2027){
        return __( 'Buy now', 'woocommerce' );
        }
    else{
        return __( 'Add to cart', 'woocommerce' );
    }
}
add_filter( 'woocommerce_product_single_add_to_cart_text', 'translate_add_to_cart', 10, 3 );

// =========================================================================
// DISPLAY PRODUCT CATEGORIES
// =========================================================================
function woocommerce_product_category( $args = array() ) {
    $woocommerce_category_id = get_queried_object_id();
  $args = array(
      'parent' => $woocommerce_category_id
  );
  $terms = get_terms( 'product_cat', $args );
  if ( $terms ) {
      echo '<ul id="myFilter" class="woocommerce-categories">';
      foreach ( $terms as $term ) {
          echo '<li class="woocommerce-product-category-page">';
              echo '<a href="' .  esc_url( get_term_link( $term ) ) . '" class="btn-filter ' . $term->slug . '">';
                echo $term->name;
              echo '</a>';
          echo '</li>';
      }
      echo '</ul>';
  }
}
add_action( 'woocommerce_archive_description', 'woocommerce_product_category', 10 );