There are four ways to say “the” in Spanish: el, la, los, las
The definite article (the) agrees with its noun in gender (feminine or masculine) and number (singular or plural).
1.) Masculine singular nouns go with “el”.
2.) Feminine singular nouns go with “la”.
el libro (the book) el papel (the paper)
la mesa (the table) la manzana (the apple)
3.) Masculine plural nouns go with “los”
4.) Feminine plural nouns go with “las”
los libros (the books) los papeles (the papers)
las mesas (the tables) las manzanas (the apples)