The default language on Windows 10 is English, but you can easily switch to any other language of your choice (except for Windows Single Language edition). If you're unsure about changing the language on Windows 10, follow the steps below.

1. Add Your Preferred Language
Step 1: Navigate to Start (1) => Settings (2).

Step 2: Choose Time & Language.

Step 3: Select Language (1) => Add a Language (2).

Step 4: Search for the language you want to install (1) => click on that language (2) => Next (3).

Check the boxes for the options (4) except for Set as my Windows display language. Click Install (5) to install the new language.

2. Changing Language on Windows 10
Step 1: Open Start => Settings => Time & Language => Language.
Next, click on the language you want to change and press the ↑ arrow to move it to the top.

Step 2: Scroll the cursor upwards and modify Windows display language (1) to the language of your choice (2).

Choose Yes, sign out now to restart your computer.

After restarting, you can experience the new language you just changed.

Additionally, you can follow the guide on how to install Vietnamese language for Windows 10 in the following link:
Guide to Install Vietnamese Language for Windows 10
For a quick and convenient language change, you can explore Windows 10 in the most convenient way and learn a new language while incorporating computer usage habits. Wishing you all success!
