Finally found the solution, I made changes in PDFservice.cs
created columns
cellProductItem = new PdfPCell(new Phrase(_localizationService.GetResource("PDFIncluding.Tax", lang.Id), titleFont));
cellProductItem.Border = Rectangle.NO_BORDER;
cellProductItem.HorizontalAlignment = Element.ALIGN_CENTER;
productsTable.AddCell(cellProductItem);
and than
string unitPrice;
var unitPriceInclTaxInCustomerCurrency = _currencyService.ConvertCurrency(orderItem.UnitPriceInclTax, order.CurrencyRate);
unitPrice = _priceFormatter.FormatPrice(unitPriceInclTaxInCustomerCurrency, true, order.CustomerCurrencyCode, lang, true);
cellProductItem = new PdfPCell(new Phrase(unitPrice, font));
cellProductItem.HorizontalAlignment = Element.ALIGN_CENTER;
cellProductItem.Border = Rectangle.NO_BORDER;
productsTable.AddCell(cellProductItem);
So, this is best and easiest way to understand the structure of PDFservice.cs
Hope it will help someone.