In this lesson, the discussion focuses on the CPU and heatsinks, which are two essential components that work together to manage heat generated by the CPU. The CPU generates a significant amount of heat, and if not properly managed, this can lead to damage or malfunction of the computer. Heatsinks, such as active and passive options including fans and water cooling, are used to dissipate heat effectively. Compatibility between the CPU and the motherboard, particularly the CPU socket, is crucial, with specific examples given, such as LGA 775 and AM4 sockets, to illustrate this point.