Hi there,

Here are those language string for those translations

COM_EASYSOCIAL_POLLS_EMAILS_POLLS_VOTE_ITEM_HEADING="%1$s voted on your polls"
COM_EASYSOCIAL_POLLS_EMAILS_POLLS_VOTE_ITEM_CONTENT="This is a notification to inform you that %1$s has voted on your polls."

Please give it a try and see how it goes.