The French expression "au fait," which is pronounced "o-feht," means "by the way, get to the point, informed."
The French expression au fait is most commonly used as an interjection meaning "by the way" or "incidentally":
Salut Pierre ! Au fait, j'ai parlé à ta sœur hier.
Hi Pierre! By the way, I talked to your sister yesterday.
Au fait can also mean "get to the point":
Je n'ai qu'une minute, donc je vais droit au fait.
I only have a minute, so I'll go straight to the point.
Get to the point (already)!
Au fait de means "informed about" or "conversant with" (though au courant de is more common). This is also the meaning of au fait in English.
Je ne suis pas au fait de sa situation.
I'm not familiar with his situation; I'm not au fait with his situation.
Note: Though it may sound similar, the expression en fait means something very different.