In this lesson, Ms. Remouna Galea, a mathematics teacher, introduces the topic of straight line graphs. She explains the concept of coordinates, including how to generate and plot them to create a straight line, starting from the origin (0,0). Ms. Galea emphasizes that the first number in a coordinate pair represents the x-coordinate and the second number represents the y-coordinate. She also illustrates how to move along the axes to plot specific coordinates, ensuring that students understand the relationship between the x and y coordinates for various examples of linear equations.