"This is not a new phenomenon."
Translation:Este não é um fenômeno novo.
The position of some adjectives may change their meaning, usually from literal (after the noun) to more abstract or subjective (before the noun). As a native speaker, I can "feel" that "novo fenômeno" means it is not like the other fenomena: it's original stuff, not seen before. And "fenômeno novo" means it is recent stuff. Even so, the context can also change the meaning, like in English.