Complex sentence: The trachea is lined with pseudostratified columnar epithelium a type of epithelium with goblet cells that produce mucins the main component of mucus, to moisten and protect the airways.
Split into simpler sentences: The trachea is lined with a layer of pseudostratified columnar epithelium, a type of epithelium. The epithelium contains goblet cells that produce mucins, the main component of mucus, which helps to moisten and protect the airways.