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The search produts, Cart, Product Cateogries are the Widget titles if you go to Appearance >> widgets >> shop sidebar and you can edit each widget and put up the new title there for that widget.
IF you want to change Search products ... text inside the search field then you have to translate the theme in your language. We have a tutotiral about theme translation here.
Please follow instructions on this article to translate the theme into your local language. https://www.webfulcreations.com/translating-wordpress-theme-local-language-using-poedit/
You can also watch this video. How to translate theme in your local language?
https://www.youtube.com/watch?v=DHiGTUgHg-c
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And about the products in products widget, they are products you can add your own products after deleting the WooCommerce demo products. in wp-admin >> Products section.