Née is used in French, and also in English, to describe a woman's last name (family name, surname) at birth. The more widely used term is her maiden name.
Né, which is used much less often, indicates the birth last name of man, when his last name is now different.
Most commonly, Née is used when a woman has changed her name due to marriage. But that is not the only use, both née and né describe the birth last name of a person who has changed their name by some other way, such as adopting a pen name.