Nouns in Spanish are either femenine or masculine. Based on the gender, we use, before the noun, an artículo definido (el OR la) which is equivalent to the English the, or we use an artículo indefinido (un OR una) which is equivalent to the English a/an. For example: el libro (the book) OR un libro (a book); la manzana (the apple) OR una manzana (an apple).
So how do we know if a noun is masculine or femenine? While there are a few rules we can follow, there are many exceptions. Here are some rules:
1) Most nouns that end in a are considered femenine; for example: la mesa (the table), la playa (the beach). However, there are exceptions, such as el agua (the water), el águila (the eagle), el área (the area), el aula (the classroom). These words use el instead of la to avoid having the two a letters next to each other . However, once these words become plural, they use la but plural, so we would have: las aguas, las águilas, las áreas, las aulas.
There are also words such as el día (the day) that end in a but use el and remain masculine when they become plural (los días).
2) Most nouns that end in o are considered masculine: el hoyo (the hole), el ojo (the eye), el toro (the bull). There are exceptions, such as la mano (the hand), which ends in o and yet uses the femenine la or una.
3) Some teachers incorrectly state that nouns that end in ma are masculine. This is not completely accurate: these nouns can be masculine or femenine. Examples:
el poema (poem), el idioma (language), el clima(weather), el tema (topic, theme), el programa (program), el sistema (system), el telegrama (telegram), el problema (the problem)
la cima (top), la cama (bed), la rama (branch), la mamá (mom), la calma (calm), la pluma (pen), la diadema (headband, diadem), la palma (palm).
4) Words that end in e can be either masculine such as el café (coffee) or feminine such as la leche (milk).
5) Words that end in the letter d will for the most part be feminine; examples: la ciudad (city), la libertad (freedom), la calidad (quality), la verdad (truth), la lealtad (loyalty).
6) Words that end in the letter l will for the most part be masculine; for example: el tamal (the food tamal), el portal (gate), el comal (skillet).
Adjectives in Spanish are placed after the noun, and they take the same form (singular or plural) of the noun they modify. For example:
1) el carro rojo (the red car); los carros rojos (the red cars)
2) la camioneta amarilla (the yellow pickup truck); las camionetas amarillas (the yellow pickup trucks)
3) la chica inteligente (the smart girl); las chicas inteligentes (the smart girls)
4) el chico hablador (the talkative boy); los chicos habladores (the talkative boys)
And just like in English, we can place an adjective after the verb:
El carro es rojo. (The car is red)
El carro está sucio. (The car is dirty)
La chica es inteligente. (The girl is smart)
Los chicos son habladores. (The boys are talkative)
Possessive adjectives are used to indicate ownership:
1) Mi pluma (my pen)
Mis plumas (my pens)
2) Tu lápiz (your pencil) - for the informal tú
Tus lápices (your pencils) - for the informal tú
3) Su cuaderno (your notebook) - for usted
Sus cuadernos (your notebooks) - for usted
4) Su cuaderno (his/her notebook)
Sus cuadernos (his/her notebooks)
5) Nuestra casa (our house)
Nuestras casas (our houses)
Nuestro coche (our car)
Nuestros coches (our cars)
6) Vuestro libro (your book) - for vosotros
Vuestros libros (your books) - for vosotros
Vuestra cobija (your blanket)
Vuestras cobijas (your blankets)
Useful links:
Real Academia Española
Study Abroad