There are some exceptions, but if you follow these three rules you will usually be correct.
Rule 1 -- if a noun ends in a vowel (a,e,i,o or u) then add S
Rule 2 -- if a noun ends in a consonant then add ES. (If the word ends in ión, drop the accent in the plural - el camion --- los camiones)
Rule 3 -- if a noun ends in Z then it changes in the plural to CES
el pez --- los peces. El lápiz --- los lápices
Try these interactive exercises to help you practise.
SET 1
SET 2
Rule 1 -- if a noun ends in a vowel (a,e,i,o or u) then add S
Rule 2 -- if a noun ends in a consonant then add ES. (If the word ends in ión, drop the accent in the plural - el camion --- los camiones)
Rule 3 -- if a noun ends in Z then it changes in the plural to CES
el pez --- los peces. El lápiz --- los lápices
Try these interactive exercises to help you practise.
SET 1
SET 2