What is non-duality in Buddhism?

I noticed some questioners on this site using the term "non-duality". What is non-duality in Buddhism? This is a well-known idea in Hinduism i.e. advaita. But does it exist in Buddhism? Is it an official term in Buddhism, or just a convenient Western philosophy terminology to describe a concept just like the terms "ontology" or "epistemology"? How is it used in Theravada and Mahayana? What are the Pali and Sanskrit terms for it? AN 10.29 seems to have the word "advayam" which Bhikkhu Sujato translates as "non-dual" but Bhikkhu Bodhi translates as "undivided". Not sure if this is related.