It is used to express agreement, understanding, or certainty. It's a polite and slightly formal way to say "yes" or "sure".
Here are some examples of how it can be used:
* "Voulez-vous du café ? - Bien entendu." (Would you like some coffee? - Of course.)
* "Je suis d'accord avec vous. - Bien entendu, c'est un point important." (I agree with you. - Of course, that's an important point.)
* "Tu peux m'aider ? - Bien entendu, avec plaisir." (Can you help me? - Of course, with pleasure.)
"Bien entendu" can also be used to emphasize a point or to show that something is obvious or expected.