1. Go to Translate My Store App
2. Go to "AI & Auto Translation" page by clicking the pointed button shown in the screenshot below. (If you want to translate everything manually, you can go to the "manual translation" page)
3. You just need to translate the product text in the App. Once the translation is available, "Multiple Google Shopping Feeds" will pick the right translation automatically for your Ads for different languages.
To translate the product text, you can setup the filter as shown in the screenshot below, and then click the "Load Items" button. You can translate them right there.
If there are questions about review translation, please send an email to firstname.lastname@example.org, and includes your store URL. Then we will help out.