Snowflake's External Functions allow users to leverage code from outside Snowflake, enabling them to access API endpoints using SQL within the platform. This feature increases available possibilities within Snowflake, reduces data pipeline needs, and facilitates integration with external APIs. Setting up External Functions requires some software engineering expertise, especially for creating new APIs. However, with an existing API, it's a relatively easy process. The tutorial demonstrates how to create an external function to enrich sales leads with a ranking score from a machine learning model API, integrating the API with Snowflake and authenticating usage. Once created, the external function can be used to enrich data in views or tables, providing valuable insights for business decision-making. While there are advantages to using External Functions, such as data enrichment without external pipelines, there are also disadvantages, including time and opportunity costs required for integration and maintenance.