Go to Theme setting -> Language preview
– First, you have to duplicate your current theme to use for 2nd language
– Copy a preview link of the 2nd theme
– Go to Navigation > Create Language menu. Then paste preview link for 2nd menu
Show the Menu on Header of the original theme. Go to Theme Setting> Language Preview
– Now go to Customize the 2nd store then translate the text
Note: this way is not the perfect solution because you can not translate the product, blog, page so we do not recommend, if you need a perfect solution so we recommend using the third-party app like Weglot.