it is in the public realm that we learn about each other, through observation and participation Je doit parler de sa en 250 mots. Aidez moi s'il vous plait !

You could say that observation and participation is the key to learn about others. But it's not only in the public realm where we could do that. Public realm must have some qualities to make people want to live and work in. Because you'll of course learn about each other, you'll talk to them, start to know them etc. Observation allow to learn about your environment (here : public realm), to seek every details about it.
Participation allow to communicate with people, to share with them etc.

C'est un début, à toi d'étoffer l'histoire.

En espérant t'avoir aidé.