The video discusses the third normal form (3NF) in database normalization, building on previous lessons about the first and second normal forms. It emphasizes that for a table to be in 3NF, it must meet the criteria of being in second normal form and should not have transitive dependencies. A transitive dependency occurs when a non-primary attribute depends on another non-primary attribute. In this case, the score table was updated to include exam name and total marks, where the primary key is a composite of student ID and subject ID. The exam name is dependent on both student and subject, while total marks is determined by the type of exam, which itself is a non-primary attribute. Therefore, total marks is considered to be transitively dependent on the primary key. This illustrates how normalization helps eliminate redundancy and ensures that all attributes in a table depend only on the primary key.