Il est sûr de son affaire = He will pay for it; He will catch it.
Je ne dis pas mes affaires aux autres = I do not tell others my plans (or business); I keep my concerns to myself.
J’entends votre affaire = I see what is to be done for you.
Ils parlent affaires = They are talking business.
Ils parlent boutique = They are talking shop.
C’est une triste affaire = It is a sad business.
S’attirer une mauvaise affaire = To get into a mess, scrape.
Quand on a de l’esprit, on se tire d’affaire = When one has brains, one gets out of any difficulty.
[Distinguish between se tirer and s’attirer.]