one, you, we
We can use one, you or we to talk about people in general, including the speaker and hearer, and not one person in particular.
- One can never know what to expect from politicians. (Or also You/We can never know.)
- In these situations, you must never lose your hope.
- We are human, and will always make mistakes.
One is more formal than we or you, and is rarely used in spoken English. However, the possessive determiner one’s is a little more common.
- Education always changes one’s life for the better. (Or also your/our life.)
- Poverty eats up one’s dignity.
Subject, object, etc.
One, you, we can be used as subject or object, or and they are often used in their reflexive form (oneself, yourself, ourselves).
- Sometimes the government treats you/us as if you/we were a child.
- There is the tendency to just lie down and let life treat one as it deems fit.
- Success and failure always teaches you/us something about yourself/ourselves.
- Helping others helps oneself.
We can normally choose one pronoun or the other for generic reference, but what is important is that we keep consistency throughout the text.
- You never know what your future will bring you.
- We never know what our future will bring us.
You never know what our future will ...
A group of people
In English we often use they to refer to people in general or a more specific group of people that does not include the speaker or hearer, such as people in a country, city, place, or authorities, police, etc.
- They don’t like strangers in this village.
- They are going to raise our taxes this year.
- They are going to open a new pub opposite my house.
Singular reference (= he or she)
In informal English, we use they, them or their to refer to one generic person who could be male or female. This use is considered incorrect by many grammarians, but it is very common, even in written language.
- A good journalist should never reveal where they get their information.
- Before the class, every student said their name aloud.
The use of they, them, their for generic singular reference is often preceded by an indefinite singular pronoun.
- Someone has left their suitcase in the taxi.
- Everyone accepted, didn’t they?
- Nobody wanted to give us their phone number.