Function words are words that have little lexical meaning but serve to express grammatical relationships within a sentence. They include categories such as prepositions, conjunctions, articles, and pronouns. Examples of function words are "and," "but," "the," and "she." These words help to connect ideas and provide structure to sentences, making them essential for clear communication. Unlike content words, which carry specific meanings and include nouns, verbs, and adjectives, function words are more about the role they play in a sentence. They help to indicate tense, mood, and relationships between different parts of a sentence, ensuring that the overall message is coherent and understandable.