The speaker gave a talk about building a semantic search application in Python using an open source framework called Haystack. They explained the concept of semantic search and the limitations of keyword search. They also discussed the different types of language models, from extractive models to generative models, and how they can be used for question answering and retrieval. The speaker then introduced the Haystack framework and its components, such as retrievers, readers, and answer generators. They provided code examples and demonstrated how to build a pipeline for extractive question answering and generative question answering. In the end, they talked about the benefits of using large language models and the importance of prompt engineering. They also mentioned that Haystack is an open source project and welcomed contributions.