Very smart! You can clearly see that the milk is taking the shape of the container. So, its shape is changing. But, its volume doesn't change. The amount of milk (about $$0.2 \, \mathrm{litres}$$) remains the same, whichever vessel you put it in.
In other words, liquids have a definite volume, but, they don't have a definite shape. They take the shape of the container that holds them.

A liquid's volume doesn't change unless we heat/cool it, etc. If you take a 1 Litre bottle of your favourite fruit juice, you cannot increase it to 2 Litres!