Teacher: definition

Impersonal pronouns: We can use impersonal pronouns to talk about people in general or for unspecified objects.

• They don't speak Italian in this part of the country.
• You really can't find anything in this shop.
• One can never be too careful (note that in everyday English, people usually use 'you' instead of 'one' - You can never be too careful)

they / them / their

We use they / them / their in singular when we talk about someone who is either male or female, to avoid saying 'he or she'

• If anyone doesn't like it, they can leave.
• Someone has left their umbrella behind.
• When a friend upsets you, do yo tell them?