a term used for "that" or "which" in English, often used in phrases to connect ideas.

a conjunction meaning "that."

कि

English Usage: She said that she would come.

Hindi Usage: उसने कहा कि वह आएगी।

used in questions as "what."

can mean "which" when referring to choices.

कौन सा

English Usage: Which way should we go?

Hindi Usage: हमें कौन सा रास्ता लेना चाहिए?