Functions in Python serve as fundamental components that enhance code modularity, reusability, and adherence to the DRY principle, thereby simplifying testing and improving code readability. They promote isolated functionality through scoping and are a counterbalance to the overuse of classes in some instances. Key practices for writing better functions include self-documenting names, adhering to the Single-responsibility principle, keeping functions concise, managing small interfaces, and using type hints and consistent return types for clarity. Avoiding global variables and mutable default arguments helps maintain function purity and prevent unexpected behavior. The text also encourages engagement with a community for further discussion and offers coaching for building applications, underscoring the importance of continuous learning and collaboration in coding.