Learn French: On invite notre voisin à la soirée. - We are inviting our neighbor to the party.

In everyday French, the pronoun on is used to mean "we". However, grammatically, on is a singular pronoun. This means it always takes the third-person singular verb form, exactly like il (he) or elle (she). That is why we use invite instead of the "we" form invitons.

If the verb follows the rules for "he/she", why do we use notre (our)?

Even though on acts like a singular pronoun for the verb, the actual meaning of the sentence is still "we". Because the real-world meaning is "we", you use the possessive adjective for "we", which is notre (our). If you used son, the sentence would mean "We are inviting his/her neighbor."

Could we use nous for this sentence instead?

Yes, you could say Nous invitons notre voisin à la soirée. That is grammatically correct and means the exact same thing, but it sounds a bit formal or like something you would read in a book. In spoken French, people prefer on.

I learned that soir means evening. Why does soirée mean "party" here?