Any product that comes from either plants or plant-based components is vegan. This milk is derived from the white-colored meat of a coconut. You do not have to be confused; the white part of it is called coconut meat and it is vegan. Therefore, the milk made from it is also vegan.
 
Coconut milk is one of the more popular plant-based alternatives to dairy milk. You may not use it to make tea, like you would with livestock milk. However, you can use coconut milk and other plant-based ingredients to make vegan desserts. This is why many regard it as a substitute for the milk made from livestock.
 
I wonder what prompted you to ask this question, though. Whether coconut is a vegetable or fruit, is a more talked-about matter than this. In fact, I have not seen anyone else asking this question.