what does [ mean in json code example

Example 1: json object

var myObj, x;
myObj = {"name":"John", "age":30, "car":null};
x = myObj.name;
document.getElementById("demo").innerHTML = x;

Example 2: json full form

JSON stands for JavaScript Object Notation. 
It is a lightweight format for storing and transporting data. 
It is often used when data is sent from a server to a web page. 
It is "self-describing" and easy to understand.