The message notification-bundle-header-edit-user-talk currently says:
$1 and $4 {{PLURAL:$5|other|others}} {{GENDER:$2|left}} a message on {{GENDER:$3|your}} talk page.
If there are multiple people, it's a bit weird that they left just one message. Maybe it should say "left messages" instead of "left a message".
(See also T121327 for another issue with the same message.)