It made its appearence when Goku did a final battle with Bills.
To become a Supersayain God,one must obtain powers from Five Sayians.
Currently now,Goku is the only one to achieve this form.
The power of this form is great enough to allow Goku to fight nearly on par with the God of Destruction Bills.
When Goku Transform into Super Sayian God,it gets red coloured.
Here look at it: