How to add vertical ruler in Visual Code?

To add vertical line to Visual Code on Mac (it should work the same way on Linux/ Windows), go to Code > Preferences > Settings and find editor.rulers then add 80 or any values that you want VS Code to display a vertical line.

// Place your settings in this file to overwrite the default settings
{
    "editor.tabSize": 2,
    "cSpell.language": "en,fr",
    "editor.rulers": [80]
}