Where can i learn how qml works?

[tuxit]

Hello,
I want to know what happens behind the scene when i wrote

Rectangle{
width:40
height:40
color:"blue"
 
}

Rectangle{
width:40
height:40
color:"blue"

}

To copy to clipboard, switch view to plain text mode 

Can you advise some where to read, i could not find so far
thanks