Creating an online store, you should care about how to hide from search engines for duplicate pages (for example, on the website will be multiple items with the same description). Or You want the contents of the specific page is displayed only for users, but for search engines to index it. Ensure Your site is not included in the ban Google or Yandex, you need to create a special file robots.txt. This file is in the root folder of your site and contains information about the pages that you do not want to index.

If You don't want to go to the programmer, to put it another link module need "NeoSeo Generator robots.txt". It allows you to automatically generate a file that you will be able to fill the "forbidden" links themselves using their admin panel.

Attention! The robots.txt generator module is already installed in such developments and does not require an additional purchase: “Build 24” for OpenCart 3.0

Discussion, questions and answers, support module Generator robots.txt for OpenCart in this thread on the forum: https://www.opencartmasters.com/forum/22-robotstxt/.
Link to installation instructions