The causative form is, in most cases, used to express the idea of having something done by someone or of causing something to happen.
It is formed with the verb faire + infinitive.
Il a écrit la lettre. He has written the letter.
Il a fait écrire la lettre par son avocat. He had the letter written by his lawyer.
Il répare sa voiture. He repairs his car.
Il fait réparer sa voiture. He has his car repaired.
Elle fait le ménage. She is doing the housework.
Elle fait faire le ménage. She has the housework made.