how to translate some text into multiple language?

Our theme can work on multiple language and normally you have 3 ways to translate things in magento site (Note that: We dont guarantee themes to be compatible with mageplaza pakage)

1.  Translate inline (magento default function), you can refer the instruction here: 

https://docs.magento.com/user-guide/system/translate-inline.html

2. Or you can use the mageplaza package, please refer and follow the instruction here: 

https://www.mageplaza.com/magento-2-extensions/language-packs.html

Even that, you can't translate everything in your site, for example the article or the product description. 

3. You can refer this document to change string manually

https://devdocs.magento.com/guides/v2.4/frontend-dev-guide/translations/translate_practice.html