The lesson discusses the different types of computer cards and interfaces, including AGP, PCI, PCI-Express (PCI-E), and M.2, highlighting their various uses and compatibility with motherboards. It explains that while network and sound cards are often not upgraded in home settings, they can be replaced or added with dedicated versions when performance improvements are needed. The teacher illustrates these concepts using a motherboard, explaining slot types, compatibility, and how expansion cards like graphics cards connect.