In Lesson 43, the vocabulary necessary to describe family members is introduced, covering terms for parents, siblings, and extended relations like in-laws and cousins. The lesson uses a family example, including names such as Guido and Alessia, to demonstrate relationships like spouses, children, grandparents, and the intricate connections of extended family members, including uncle Arturo, aunt Cristina, and their cousins Vittorio and Manuela. The lesson concludes with exercises to reinforce Italian family vocabulary comprehension.