This introduces JSON object into Scratch. If you are not familiar with JSON then you can refer this example in which test is a variable: Create Json will set the var block to the value needed. (json).(var) will give the value of it. More examples of the usage can be seen inside the preoject.
------------NOTE------------ 1. If the variable contained in the object is not defined, it will return undefined. 2. If you are using any commas then the JSON won't work properly.