In French, a noun is always feminine or masculine. It is introduced by a determiner, which usually indicates the gender of the noun.
When a noun refers to a person, the gender is determined by the person's sex (although some exceptions do exist). In general, the feminine form of the noun is formed by adding an -e to the masculine noun. Note that the addition of the -e changes the pronunciation in some words:
There are cases when the feminine form of the noun changes more drastically.
TIP: In general, when the masculine noun ends in -e, the feminine noun remains unchanged. Only the determiner or the context indicates if it is a feminine or masculine noun.
The gender of animals is often arbitrary. Some animals are always masculine (un escargot, a snail), others are feminine (la fourmi, ant). However, for some animals there are irregular masculine and feminine forms.
Gender can often be figured out from the ending of the word.
Masculine: Typically, words ending in: -age, -ment, -eau, -phone, -scope, -isme
Feminine: Typically, words ending in:-tion,-sion, -té, -ette, -ance, -ence, -ie, -ure, -ode/-ade/-ude
NOTE: Not every word that ends in “e” is feminine. Look at the last 3-4 letters of the word, not just the last letter.