In Chinese culture, tapping the table is a way to show gratitude and appreciation when someone refills their cup. It is a common gesture of politeness and respect during meals or tea ceremonies. When a guest's cup is empty or nearly empty, and someone else refills it, the guest may respond by tapping their fingers lightly on the table near the cup.
This action is a way of saying "thank you" without having to interrupt the conversation or verbally express gratitude directly. It is considered a polite and humble way of acknowledging the act of kindness from the person who refilled the cup.
Additionally, when someone taps the table after you refill their cup, it indicates that they are content with the amount of liquid you poured, and it signals that you can stop pouring more if you were still in the process of doing so.
Overall, tapping the table when a cup is refilled is a cultural tradition that reflects the Chinese values of respect, gratitude, and maintaining harmonious interactions during communal dining or tea drinking.