The video provides an overview of three types of relationships in relational databases using a movie rental system as an example. It focuses on four entities: member, rental, movie, and driver’s license. The first relationship discussed is one-to-one, where each member has a unique driver’s license for verification, ensuring that one driver’s license corresponds to one member. The second relationship is one-to-many, where a single member can have multiple rentals, but each rental is tied to only one member. The final relationship explored is many-to-many, which involves movies and rentals. Here, one movie can have multiple rentals, and each rental can involve multiple movies; thus, a junction table is necessary to connect the two, containing two foreign keys that are primary keys of each entity involved. The video illustrates these relationships and explains how primary and foreign keys function to establish them, laying the foundation for understanding database design through record correlation.