[{"_id":"5d752c544f4f1c0f1c93eb23","name":"estacionamento um","parkingSpace":[{"_id":"5d752cf54f4f1c0f1c93eb26","name":"vg001","excluded":true},{"_id":"5d752cf54f4f1c0f1c93eb27","name":"vg001","excluded":false},{"_id":"5d75339bc411423a9c14ac52","name":"vg002","excluded":false}]},{"_id":"5d7706b60d354b72388a38f4","name":"estacionamento dois","parkingSpace":[{"_id":"5d77078a5173bb63bc87b7ca","name":"vg004","excluded":false}]}]

db.collection.aggregate([{$match:{"parkingSpace.excluded":false,}},{$project:{parkingSpace:1}},{"$group":{"_id":"$_id","count":{"$sum":{"$size":{"$filter":{"input":"$parkingSpace","as":"el","cond":{"$eq":["$$el.excluded",false]}}}}}}}])