It's the plural masculine form of "beau", meaning "beautiful" or "handsome".
Here are some examples of how "de beaux" can be used in a sentence:
* "J'ai vu de beaux paysages." (I saw beautiful landscapes.)
* "Il y a de beaux bâtiments dans cette ville." (There are handsome buildings in this city.)
Note: "De beaux" is often used with a noun, like "de beaux paysages" (beautiful landscapes), "de beaux souvenirs" (beautiful memories), "de beaux rêves" (beautiful dreams), etc.