How to fetch array data from a table using aggregate

Working with Data
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5

sample document for guardian is

{
  "_id": {
    "$oid": "62908343716f52001696cc9b"
  },
  "wards": [
    {
      "admissionNumber": "Sil 0020",
      "schoolCode": "SC227043"
    },
    {
      "admissionNumber": "Sil 0023",
      "schoolCode": "SC227043"
    }
  ],
  "verify": false,
  "regPoint": 4,
  "completeRegistration": true,
  "email": "kehindefayenuwo@yahoo.com",
  "schoolId": {
    "$oid": "624f9790a900d000165b543e"
  },
  "password": "$2a$10$60aNQeReDfHohft1P5WDjuWwfvCtJZlr.7sjUbDU8K8TpQgs5U1oG",
  "__v": 0,
  "otp": "3654",
  "phoneNumber": "8028944791",
  "address": "22 apata alakia ibadan",
  "firstName": "taiwo",
  "lastName": "omotola",
  "about": "life",
  "imgUri": "https://res.cloudinary.com/asm-web/image/upload/v1654100090/ukv0qydhcpsfu1ssg7nd.jpg"
}