The Korean particles "을" and "를" are used to indicate the object of a verb in a sentence. "을" is used after a noun that ends in a consonant, while "를" is used after a noun that ends in a vowel. For example, in the sentence "사과를 먹다" (to eat an apple), "사과" (apple) is the object, and "를" is attached because "사과" ends in a vowel. These particles help clarify the role of nouns in a sentence, making it easier to understand who is doing what. In Korean, the subject usually comes first, followed by the object marked by "을" or "를," and then the verb. This structure is essential for proper sentence formation in the language.