"These houses are big and beautiful."
Translation:Ezek a házak nagyok és szépek.
I don't understand why i need the "a." Isn't "ezek" a sufficient article?
"Ezek" is not an article. It is a demonstrative. And, unlike English, Hungarian always requires a definite article between the demonstrative and the noun. This is just how it is. It needs to be that way.
"These houses" equals to "ezek a házak".