In English, a definite article refers to a specific noun. Since we don’t have gender associated with our nouns, and we don’t change the article according to number, we use only one: The.
The car. The girl. The cars. The girls.
In Spanish, nouns have both gender and number and the definite articles change to reflect that, so we have four options.
Masculine, singular: El. Masculine, plural: Los. Feminine, singular: La. Feminine, plural: Las.
El carro = the car, since carro is masculine and singular. La niña = the girl, since niña is feminine and singular. Los carros = the cars, since carros is masculine and plural. Las niñas = the girls, since niñas is feminine and plural. They all mean “the”.
In English, the indefinite articles refer to vague or unknown quantities of a noun, it is not specific. We use: A, an, & some.
A car. A girl. An elephant. Some cars. Some girls. Some elephants.
In Spanish, once again we need to reflect the gender and number of the noun with the article, so we have four options: Un(o), unos, una, unas. If you’re thinking that the word uno means one, you’re correct. In this case, when uno appears before a masculine, singular noun, we drop the -o on the end. So we have:
Un carro. Una niña. Un elefante. Unos carros. Unas niñas. Unos elefantes.
Make some flash cards with the 8 articles and practice with the nouns that you have already learned.