What is the sound of one hand clapping?
This depends a lot on what you mean by clapping. Conventional clapping requires 2 hands to do, so if you define clapping as the sound that occurs when 2 hands hit each other, this cannot happen. However, if you define it as the sound when one part of the skin touches another part in a fast manner, then we can expect a sound similar to the conventional sound in some cases and a different sound in others. Surely, without a voice output device, it would be hard to give a concrete example.
The phrase the sound of one hand clapping comes from a well-known Zen koan, which is a paradoxical question or statement used in Zen Buddhism to provoke deep thought and meditation. The purpose of a koan is to challenge conventional thinking and push the student to achieve a higher level of understanding.

The question itself has no definitive answer and is not intended to have one. The sound of one hand clapping is an example of a nonsensical statement that is meant to disrupt the logical mind and encourage a more profound form of contemplation. The goal is for the student to look beyond the literal meaning of the question and to reach a more intuitive or spiritual understanding.