One of the first things I like to teach English speakers are the words for the word "the". There are 4 words in Spanish that can be translated to mean "the", namely el, la, los, las. These words are used when refering to something - either masculine singular, plural or feminine singular or plural.

For example:
the book = "el libro"
the chair = "la silla"
the books = "los libros"
the chairs = "las sillas"