Updated: Sep 7, 2020
The pronoun "on" is a subject pronoun (it replaces a noun).
It is a third person singular pronoun (je; tu; il/elle/on; nous; vous; ils/elles) and therefore, verbs following "on" are conjugated the same way as verbs in the "il or elle" form.
However, the pronoun "on" is used as 'we' in modern spoken French.
It can also mean: one, you, they/ people/ someone.
Let's have a look at these different meanings!
1. "on" as an indefinite pronoun
The use of 'on' as an indefinite pronoun is very similar to the use of 'one' in English.
It is a gender-neutral, third person singular pronoun.
This pronoun is used when talking about people in general.
Example: Dans les Alpes on peut skier. In the Alps, one can ski.
You will note that in today's spoken English, you tend to say: you can ski.
This is the reason why "on" can also be translated as 'you' in English.
Therefore, when translating a sentence with 'you', you should always ask yourself the question: Are we talking about people in general (anyone can ski) or are we talking to one person in particular?
If we are talking about people in general, you need to use "on".
If we are talking to one person in particular, you need to use "tu" or "vous".
2. "on" for someone/ people or they
The pronoun "on" can refer to a person or to people whose identity is not really known or not really important.
On dit que la première année de mariage est la plus difficile.
People say that the first year of marriage is the most difficult.
On n'en fabrique plus.
They don't make them anymore.
On m'a dit que tu étais malade.
Someone told me you were ill.
3. "on" as an equivalent for "nous"
The use of "on" instead of "nous" is very frequent in modern spoken French.
Even though the subject pronoun refers to a group of people, the verb is conjugated in the third person of the singular.
On a une fille qui habite à Londres.
We have a daughter who lives in London.
On est heureux.
We are happy.
You can't use the singular verb form without including the "on".
You can say: ma sœur et moi mangeons ensemble for nous mangeons ensemble
BUT YOU CAN'T SAY: "ma sœur et moi mange ensemble" for on mange ensemble.
Although it is not uncommon for French people to add the extra on in order to make it work: "Ma et sœur et moi, on mange ensemble." it is not correct French and you should always use the nous form of the verb with " ..x.. et moi".