General Rules
* Most nouns: Add -s to the end.
* Nouns ending in -s, -x, -z, -ch, or -y: Add -es to the end.
Examples:
* Singular: libro (book) Plural: libros (books)
* Singular: lápiz (pencil) Plural: lápices (pencils)
* Singular: pez (fish) Plural: peces (fish)
* Singular: flor (flower) Plural: flores (flowers)
* Singular: rey (king) Plural: reyes (kings)
Special Cases
* Nouns ending in -a: Add -s if the stress is on the first syllable. Add -as if the stress is on the second syllable.
* Singular: casa (house) Plural: casas (houses)
* Singular: mamá (mom) Plural: mamás (moms)
* Nouns ending in -o: Add -s if the stress is on the first syllable. Add -os if the stress is on the second syllable.
* Singular: gato (cat) Plural: gatos (cats)
* Singular: teléfono (phone) Plural: teléfonos (phones)
* Nouns ending in -ción: Add -es to the end.
* Singular: nación (nation) Plural: naciones (nations)
* Nouns ending in -ión: Add -es to the end.
* Singular: canción (song) Plural: canciones (songs)
* Some nouns are irregular:
* Singular: hombre (man) Plural: hombres (men)
* Singular: mujer (woman) Plural: mujeres (women)
Important Note: Spanish nouns are either masculine or feminine. The plural ending will change based on the gender of the noun.
Let me know if you want to practice forming plurals with some specific nouns!