Yes, coconut sugar (aka palm sugar) can easily be substituted cup for cup for white granulated sugar. It comes as either crystals or a paste form. Crystallized for will be same as white sugar. If you use the paste form, you may have to reduce the liquid in your recipe slightly.

However, some are advocating for not using palm sugar because it is not really a sustainable product. It is easily made and unrefined, however, a coconut palm tree cannot produce both a coconut and palm sugar because the palm sugar is made from the sap that the coconut blossom produces. The blossom is destroyed when harvesting the sap, therefore no coconut. Less coconuts means less coconut palm trees and many are afraid that the new practice of converting coconut orchards into coconut sugar production orchards only will eventually cause endangerment issues. Read more about this on The Truth About Coconut Palm Sugar article.