It denotes an array.
If you have a class like :
private class pax{
public string type {get;set;}
public int count {get;set;}
}
then you can deserialize to an array of this called paxs:
private class myObject{
public pax[] paxs {get;set;}
}
myObject mo = JsonConvert.DeserializeObject<myobject>(jsonString);
</myobject>