I get these yummy drinks that have tapioca balls in them often so I'm very familiar with it. Tapioca is a flavorless starch made from the cassava root. It's used primarily in desserts i.e. tapioca pudding and my drinks. Tapioca flour is used as a thickener like corn starch or flour. Not much nutritional value in it as far as I can tell so might as well just skip it. Give your lo something with more nutrition. Sago is pretty similar.