Parts of speech help us understand how words work in a sentence. For example, in the sentence "The cat sleeps on the bed," each word has a role. "The" is an article, "cat" is a noun, "sleeps" is a verb, "on" is a preposition, and "bed" is a noun. Another example is "She runs fast." Here, "She" is a pronoun, "runs" is a verb, and "fast" is an adverb because it tells how she runs. Knowing parts of speech helps us write and speak clearly.