This lecture by the instructor covers the Source Coding Theorem, introducing various source models, determining their entropy, and deriving a fundamental limit about the asymptotic behavior of optimal source coding. The lecture explains the setup of source coding, the concept of regular sources, and different source models like the Coin-Flip and Sunny-Rainy sources. It also discusses the distinction between different source types and the entropy rate of a source. The lecture concludes with examples and exercises on calculating entropy for different sources and determining the regularity of a source.