When creating a new pane, simply change the locale from All Locales to your Targeted Locale
All Locales: Pane will be always visible to everyone; regardless of their locale.
Targeted Locale: Pane will only be shown for that particular locale.
Note: Locales list is only visible if there is more than one locale enabled in DotNetNuke Site | Admin > Languages.
then, Simply Create Pane as you normally would.