Drupal Commerce is different from other eCommerce platforms in that it is a open source software and can be used freely without any restrictions. However, a certain amount of effort is required to set up and maintain the software.
At a high level, the answer to your question is yes: Drupal Commerce is open-source and free to use. However, there are some caveats to consider before using the software. Here are some key points to keep in mind:
• Installation and basic configuration of Drupal Commerce require some technical skills – you may need to hire a developer or consultant to help you get set up properly.
• You will need to choose and configure payment gateways, shipping and tax rules as part of setting up your store.
• While the core software is free, you may need to purchase additional modules or themes to extend functionality or customize the look and feel of your store.
• You will need to provide your own hosting for Drupal Commerce.
For more information about setting up and using Drupal Commerce, see https://www.drupal.org/docs/8/commerce/getting-started-packages-and-installation or search the Drupal Commerce community forums at https://www.drupal.org/forum/tags/drupal-commerce.