Merciありがとう

Explanation

The polite formula comes in two versions, and it is not that one is more polite than the other: the person in front of you decides. French has two ways of addressing someone. To a friend, to family, to anyone you would say salut to, it is te: s'il te plaît. To a stranger, to someone older, to a shopkeeper — or to several people at once — it is vous: s'il vous plaît. Lucas says s'il te plaît to Camille because they are friends; at a café counter the same request becomes s'il vous plaît. For now, keep both formulas as they are; the full system comes later. And when someone thanks you, the ordinary reply is de rien: the favour doesn't count, say no more about it.

Explanation

To approach someone, French has two words, and they do different jobs. Excusez-moi stops the person: you say it before asking a stranger for something. Pardon is for a small collision — you bump into someone, you squeeze past them — and also, on its own, to ask someone to repeat. Lucas uses both at the top of the dialogue: he hails her, then apologises. Then comes ça va, the everyday all-purpose phrase. The same two words serve as the question and as the answer, and nothing moves between them: only the voice changes, exactly as with "D'accord ?". Ça va ? rises at the end; Ça va ! falls. To say a little more, add bien: Ça va bien.