[{"_id":"new-request","series":[{"_id":"5e9c282373fba9a3d4ecb9bf","day":"Saterday","hour":13}]},{"_id":"visit","series":[{"_id":"5e9c282373fba9a3d4ecb9bf","day":"Saterday","hour":13},{"_id":"5e9c282a73fba9a3d4ecb9c0","day":"Friday","hour":13},{"_id":"5e9c286f73fba9a3d4ecb9c1","day":"Sunday","hour":13},{"_id":"5e9c287373fba9a3d4ecb9c2","day":"Sunday","hour":13},{"_id":"5e9c28b8cef225afcc27c144","day":"Sunday","hour":13},{"_id":"5e9c28ca295960a654b70c5c","day":"Sunday","hour":13},{"_id":"5e9c28d5b072281a6ce571f1","day":"Sunday","hour":13}]}]

db.collection.aggregate([{$unwind:"$series"},{$group:{_id:{name:"$_id",day:"$series.day"},count:{$sum:1}}},{$group:{_id:"$_id.name",series:{$addToSet:{day:"$_id.day",count:{$sum:"$count"}}}}},{$project:{_id:0,name:"$_id",series:"$series"}}])