The document explains conjunctions, which are words that connect sentences, phrases, or clauses to enhance coherence. It details the types of conjunctions: coordinating (e.g., 'and,' 'but'), subordinating (e.g., 'because,' 'although'), and correlative (e.g., 'either...or,' 'neither...nor'). The text emphasizes their importance in improving writing clarity and demonstrating relationships between ideas.