what is "on" and what are les formes toniques des pronoms personnels?

[Yan Fang]

"on" is the third person? what does that mean?

Also, what are atones (unstressed) and toniques (stressed) pronoms personnels?

[Erwan]

on is a substitute for "the people we are talking about" and we are included in this group.
On va à la plage : We are going to the beach

Pronoms personnels atone / tonique

je/moi

tu/toi

il/lui

elle/elle

nous/nous

vous/vous

ils/eux

elles/elles

e.g. : Regarde moi. Look at me

Moi, je l'ai. Me, I've got it (It's a litteral translation but I'm not sure this is really used). This construction strenghtens the subject je.

C'est à moi. It's mine.