In this lesson, Ramon focuses on calculating the area of a triangle, specifically when it is not a right-angled triangle. He introduces a new formula for the area, which involves applying the sine and cosine rules and understanding how to determine the triangle’s base and height. The lesson involves practical exercises and using trigonometric relationships, including the sine of an angle, to perform necessary substitutions in calculations. Additionally, he emphasizes the importance of finding the right dimensions and applying them correctly to compute the area of the triangle.