Cupping your hands together to form a bowl is a way of measuring in Ayurveda. Anjali Pramana is the measurement of volume.
It is believed for optimum digestion we should aim to consume 1 anjali of food, 1 of liquid and leave 1 anjali empty to allow for proper digestion of our food.
Another example that not one size fits all and that we all have varying needs.
It is a handy way to visualize when eating your meals and I personally find it makes me more mindful.