Dictionary

(the third-person plural) A group of people, animals, plants or objects previously mentioned.

Example: Dogs may bark if they want to be fed.

(the third-person singular, sometimes proscribed) A single person, previously mentioned, especially if of unknown or non-binary gender, but typically not if previously named and identified as male or female.

Example: They requested a seat at Friday's performance but didn't say if they preferred the balcony or the floor.

(indefinite pronoun, vague meaning) People; some people; people in general; someone, excluding the speaker.

Example: Ha, you believe the moon is real? That's just what they want you to think.

There (especially as an expletive subject of be).