It's a common expression used in both religious and secular contexts, often as a way of wishing someone good fortune or success in their endeavors.
Here are some common ways "hatzlacha" is used:
* "Hatzlacha!" - a standalone exclamation meaning "good luck!"
* "Hatzlacha b'chol ma'asecha" (הצלחה בכל מעשיך) - "Success in all your endeavors."
* "Hatzlacha ba'mitzvah" (הצלחה במצווה) - "Success in your mitzvah."
It's a versatile word that can be used in a wide range of situations, making it a useful expression to know.