Here you need to know how many litters are a measuring cup.
1 cup = 250ml = 0.25 liters.
Now, do the cross multiplication:
1 cup ----- 0.25 liters.
1.2 cups --X= 1.2 (cups * 0.25 liters)/ 1 cup = 0.3 liters
So, 1.2 cups of oil represent 0.3 liters or 300ml.