Most names for professions change if the person is masculine or feminine.
Je suis avocat, dit Jim.Je suis avocate, dit Tina.
I'm a lawyer, Jim says.I'm a lawyer, Tina says.
Je vois un acteur et une actrice sur scène.
I see an actor and an actress on stage.
Il y a un vendeur et une vendeuse.
There is a salesman and a saleswoman.
And also if referring to more than one person:
Lucie et Sarah sont chanteuses.
Lucie and Sarah are singers.
Luc et Patrick sont chanteurs.
Luc and Patrick are singers.
BUT
Masculine always wins in French!
Here are some more examples:
Voilà le président François et la présidente Angela.
Here are the president François and the president Angela.
Il y a un vendeur et une vendeuse.
There is a salesman and a saleswoman.
Le directeur rencontre la directrice.
The headmaster meets the headmistress.
Voilà le chanteur Charles Aznavour et la chanteuse Céline Dion.
Here are the singer Charles Aznavour and the singer Céline Dion.
Il y a un docteur et une doctoresse.
There is a (male) doctor and a (female) doctor.
Exceptions:
Il y a un médecin et un médecin femme.
There is a (male) doctor and a (female) doctor.
Le professeur (ou le prof) s'appelle Eric. La professeur (ou la prof) s'appelle Noémie.
The teacher's name is Eric.The teacher's name is Noémie.
-> Note that the Académie Française considers la professeure a neologism.
See also Don't use un, une when giving people's professions (zero article)
Learn more about these related French grammar topics
Examples and resources
Je suis avocat, dit Jim.Je suis avocate, dit Tina.
I'm a lawyer, Jim says.I'm a lawyer, Tina says.
Il y a un docteur et une doctoresse.
There is a (male) doctor and a (female) doctor.
Daniel est le créateur et Isabelle est la créatrice aussi.
Daniel is the creator and Isabelle is the creator too.
Je vois un acteur et une actrice sur scène.
I see an actor and an actress on stage.
Il y a un médecin et un médecin femme.
There is a (male) doctor and a (female) doctor.
Le professeur (ou le prof) s'appelle Eric. La professeur (ou la prof) s'appelle Noémie.
The teacher's name is Eric.The teacher's name is Noémie.
Le directeur rencontre la directrice.
The headmaster meets the headmistress.
Luc et Sarah sont chanteurs.
Luc and Sarah are singers.
Voilà le président François et la présidente Angela.
Here are the president François and the president Angela.
Il y a un vendeur et une vendeuse.
There is a salesman and a saleswoman.
Luc et Patrick sont chanteurs.
Luc and Patrick are singers.
Voilà le chanteur Charles Aznavour et la chanteuse Céline Dion.
Here are the singer Charles Aznavour and the singer Céline Dion.
Lucie et Sarah sont chanteuses.
Lucie and Sarah are singers.

Q&A

Gruff
Kwiziq language super star
12/09/17

Ron
Kwiziq community member
31/05/17
J'espère que cela vous aiderez.
Ron

Laura
Kwiziq language super star
28/05/17

Ron
Kwiziq community member
31/05/17
In French, you always need an article in front of a group including an adjective, and that rule applies to professions:
Paul est un professeur extraordinaire.
Otherwise: Paul est professeur. (note: no adjective, hence no article)

Laura
Kwiziq language super star
1/10/16
Aishatu
Kwiziq community member
27/11/16
David
Kwiziq community member
11 February 2018
1 reply
Is this becoming obsolete in actual practice, like in English?
Laura
Kwiziq language super star
11 February 2018
11/02/18
Bonjour David,
Not at all, quite the contrary. French is moving toward creating feminine forms for nouns that are currently masculine only, such as un pompier, which now has a feminine counterpart une pompière. There's some debate about whether this is necessary / desirable, but it's certainly not going obsolete.