The gender of nouns is always a stumbling point for people learning Spanish. In Spanish, nouns always take on a specific gender. This gender role is in addition to the traditional role nouns take on as the subject of a sentence or the direct object of a verb.
Spanish nouns are either masculine or feminine. Nouns that refer to males are always masculine, and nouns that refer to females are feminine, no matter their endings. You can’t always be sure when it comes to places or things, though.
In Spanish, certain endings are good indications as to the gender (masculine or feminine designation) of nouns. For instance, nouns that end in -o (except la mano [lah mah-noh; the hand] and la radio [lah rah-deeoh; the radio]) are most often masculine. Nouns that end in -a, -ad (la ciudad [lah seeoo-dahd; city]), -ie (la serie [lah seh-reeeh; the series]), -ción (la canción [lah kahn-seeohn; the song]), -sión (la discusión [lah dees-koo-seeohn; discussion]), -ud (la salud [lah sah-lood; health]), and -umbre (la costumbre [lah kohs-toom-bvreh; custom]) generally are feminine.
Certain nouns belonging to a theme are masculine, including
Numbers (el cuatro [ehl kooah-troh; four])
Days of the week (el jueves [ehl Hooeh-bvehs; Thursday])
Compass points (el norte [ehl nohr-teh; north])
Names of trees (el manzano [ehl mahn-sah-noh; apple tree])
Compound nouns (el mediodía [ehl meh-deeoh-dee-ah; noon])
Names of rivers, lakes, mountains, straits, and seas (el Mediterráneo [ehl meh-dee-teh-rrah-neh-oh; the Mediterranean])
Certain nouns belonging to a theme are feminine, such as
Many illnesses (la gripe [lah gree-peh; the flu], la apendicitis [lah ah-pehn-dee-see-tees; appendicitis])
Islands and provinces (la Córsega [lah kohr-seh-gah; Corsica])
If you’re not sure about a particular word’s gender, take a look at the article that precedes it for a hint. El and los are masculine forms of the, whereas la and las are feminine.