Can someone help me understand the validator functionality in addtionalFields?

 typescript
    additionalFields: {
      status: {
        type: "string",
        defaultValue: "active",
        input: false,
        validator: {
          input: userStatus,
          output: ?
        },
      },
      phoneNumber: {
        type: "string",
        input: false,
        validator: {
          input: userPhoneNumber,
          output: ?
        }
      }
    }
  },
}