This policy removes the option to change the user's menus and dialogs (UI) language from the Language and Regional Options ...

This policy removes the option to change the user's menus and dialogs (UI) language from the Language and Regional Options control panel.  This does not, however, prevent the user or an application from changing the UI language programmatically.

The policy is used only to simplify the Regional Options control panel.

If the policy is Enabled, then the user will not see the option for changing the UI language.

If the policy is Disabled or Not Configured, then the user will see the option for changing the UI language.

Note that even if a user can see the option to change the UI language, other policies may prevent them from changing their UI language.