Pali is an old language of India. Nobody grows up speaking it at home now. You meet it if you study Buddhism, because a huge set of Buddhist holy writings was kept in Pali. That set is called the Pali canon — here canon just means “the official collection of texts,” not a big gun.

Monks and scholars still read it, and some chants you hear in temples are in Pali. It is close to the kind of language people spoke in northern India around the time of the Buddha, though actually the texts were written down later. It is not the same as Sanskrit. Sanskrit is a sister old language of India and often feels more high and school-like; Pali is the one most tied to the kind of Buddhism you meet in Thailand and Sri Lanka, and in some temples in Taiwan. In English it is a specialist word: religion class, not the night market.