Hello ,
we say « une orange »
But there isn’t not really a way to tell it . I mean on some words like : UN infirmier / UNE infirmière
All depends on the word like : UN médecin , it’s the same for the feminine.
But you can say : UNE FEMME médecin
But it’s really simple for find the masculine or feminine. Ask me if you need some help on homeworks or something in French :)