--- a/browser/browser/browser.ftl
+++ b/browser/browser/browser.ftl
@@ -689,16 +689,21 @@ toolbar-button-save-page =
 # Variables:
 #  $shortcut (String): keyboard shortcut to open a local file
 toolbar-button-open-file =
     .label = Agor Ffeil
     .tooltiptext = Agor ffeil ({ $shortcut })
 toolbar-button-synced-tabs =
     .label = Tabiau wedi'u Cydweddu
     .tooltiptext = Dangos tabiau o ddyfeisiau eraill
+# Variables
+# $shortcut (string) - Keyboard shortcut to open a new private browsing window
+toolbar-button-new-private-window =
+    .label = Ffenestr Breifat Newydd
+    .tooltiptext = Agor ffenestr Pori Preifat newydd ({ $shortcut })
 
 ## EME notification panel
 
 eme-notifications-drm-content-playing = Mae peth sain a fideo ar y wefan yn defnyddio meddalwedd DRM, gall gyfyngu'r hyn y gall { -brand-short-name } ei wneud gydag ef.
 eme-notifications-drm-content-playing-manage = Rheoli Gosodiadau
 eme-notifications-drm-content-playing-manage-accesskey = R
 eme-notifications-drm-content-playing-dismiss = Cau
 eme-notifications-drm-content-playing-dismiss-accesskey = C