It's often used to describe someone who is well-informed about current events, trends, or happenings. They are aware of the latest developments and can easily participate in conversations about them.
Here are some examples of how you might use "au courant":
* "She's very au courant on fashion trends."
* "He's not exactly au courant with the latest political news."
* "Being au courant with the latest tech developments is crucial for my job."
The phrase "au courant" is considered more formal than "up-to-date" and can add a touch of sophistication to your vocabulary.