For plurals you just add an s at the end of each word as in english
perro(dog)=perros(dogs)
gato=(cat)=gatos(cats)
but if the words ends with a consonant then you have to add -es
matador(bullfighter)=matadores
for the words ending in "z"
such as "pez" (fish) you have to change this "z" for a "c" and add -es
pez(fish)=peces
veloz(fast)=veloces