How to create a multilingual online store?

You can do this by building different websites for different catalog versions — an individual website for each language version. For this, you need to upgrade to the Business plan that allows you to create up to and including five websites: https://tilda.cc/pricing-compare/. You can buy the Business plan in the "Plans and Billing" tab.

In one project, you need to connect your domain. In the domain registrar's control panel, you can create a subdomain for it that you can connect to another Tilda project in the same way using this guide: https://help.tilda.cc/customdomain. So, you can create a multilingual Catalog.

Detailed guide: Online Store and Payments Processing

If you need to have more than 2 languages, set up a dropdown menu: How To Set Up a Website Menu